diff --git a/packages/bruno-app/src/components/FilePickerEditor/index.js b/packages/bruno-app/src/components/FilePickerEditor/index.js
index 65f9046b5fc..907b98eac68 100644
--- a/packages/bruno-app/src/components/FilePickerEditor/index.js
+++ b/packages/bruno-app/src/components/FilePickerEditor/index.js
@@ -1,5 +1,5 @@
 import React from 'react';
-import path from 'utils/common/path';
+import { getRelativePathWithinBasePath } from 'utils/common/path';
 import { useDispatch } from 'react-redux';
 import { browseFiles } from 'providers/ReduxStore/slices/collections/actions';
 import { IconX, IconUpload, IconFile } from '@tabler/icons';
@@ -48,13 +48,7 @@ const FilePickerEditor = ({
         // If file is in the collection's directory, then we use relative path
         // Otherwise, we use the absolute path
         filePaths = filePaths.map((filePath) => {
-          const collectionDir = collection.pathname;
-
-          if (filePath.startsWith(collectionDir)) {
-            return path.relative(collectionDir, filePath);
-          }
-
-          return filePath;
+          return getRelativePathWithinBasePath(collection.pathname, filePath);
         });
 
         onChange(isSingleFilePicker ? filePaths[0] : filePaths);
diff --git a/packages/bruno-app/src/components/RequestPane/MultipartFormParams/index.js b/packages/bruno-app/src/components/RequestPane/MultipartFormParams/index.js
index 530468445ae..33cd651aaf3 100644
--- a/packages/bruno-app/src/components/RequestPane/MultipartFormParams/index.js
+++ b/packages/bruno-app/src/components/RequestPane/MultipartFormParams/index.js
@@ -14,7 +14,7 @@ import { sendRequest, saveRequest } from 'providers/ReduxStore/slices/collection
 import { updateTableColumnWidths } from 'providers/ReduxStore/slices/tabs';
 import EditableTable from 'components/EditableTable';
 import StyledWrapper from './StyledWrapper';
-import path from 'utils/common/path';
+import { getRelativePathWithinBasePath } from 'utils/common/path';
 import { usePersistedState } from 'hooks/usePersistedState';
 import { useTrackScroll } from 'hooks/useTrackScroll';
 import { isWindowsOS } from 'utils/common/platform';
@@ -60,11 +60,7 @@ const MultipartFormParams = ({ item, collection }) => {
     dispatch(browseFiles())
       .then((filePaths) => {
         const processedPaths = filePaths.map((filePath) => {
-          const collectionDir = collection.pathname;
-          if (filePath.startsWith(collectionDir)) {
-            return path.relative(collectionDir, filePath);
-          }
-          return filePath;
+          return getRelativePathWithinBasePath(collection.pathname, filePath);
         });
 
         const currentParams = item.draft
diff --git a/packages/bruno-app/src/components/ResponseExample/ResponseExampleRequestPane/ResponseExampleMultipartFormParams/index.js b/packages/bruno-app/src/components/ResponseExample/ResponseExampleRequestPane/ResponseExampleMultipartFormParams/index.js
index ef327f9a2b9..03faf08cbbd 100644
--- a/packages/bruno-app/src/components/ResponseExample/ResponseExampleRequestPane/ResponseExampleMultipartFormParams/index.js
+++ b/packages/bruno-app/src/components/ResponseExample/ResponseExampleRequestPane/ResponseExampleMultipartFormParams/index.js
@@ -7,7 +7,7 @@ import { updateResponseExampleMultipartFormParams } from 'providers/ReduxStore/s
 import { browseFiles } from 'providers/ReduxStore/slices/collections/actions';
 import { updateTableColumnWidths } from 'providers/ReduxStore/slices/tabs';
 import mime from 'mime-types';
-import path from 'utils/common/path';
+import path, { getRelativePathWithinBasePath } from 'utils/common/path';
 import EditableTable from 'components/EditableTable';
 import MultiLineEditor from 'components/MultiLineEditor';
 import SingleLineEditor from 'components/SingleLineEditor';
@@ -51,11 +51,7 @@ const ResponseExampleMultipartFormParams = ({ item, collection, exampleUid, edit
     dispatch(browseFiles())
       .then((filePaths) => {
         const processedPaths = filePaths.map((filePath) => {
-          const collectionDir = collection.pathname;
-          if (filePath.startsWith(collectionDir)) {
-            return path.relative(collectionDir, filePath);
-          }
-          return filePath;
+          return getRelativePathWithinBasePath(collection.pathname, filePath);
         });
 
         const currentParams = params || [];
diff --git a/packages/bruno-app/src/utils/common/path.js b/packages/bruno-app/src/utils/common/path.js
index e1b8e826f13..338a5067819 100644
--- a/packages/bruno-app/src/utils/common/path.js
+++ b/packages/bruno-app/src/utils/common/path.js
@@ -163,10 +163,60 @@ const getAbsoluteFilePath = (basePath, relativePath, shouldPosixify = false) =>
   return shouldPosixify ? posixify(result) : result;
 };
 
+/**
+ * Returns a relative path when filePath is contained within basePath.
+ * For paths outside basePath (or same path), returns the original filePath unchanged.
+ *
+ * @param {string} basePath - The base path to check containment against (e.g., collection pathname).
+ * @param {string} filePath - The absolute file path to compute a relative path for.
+ * @param {boolean} [shouldPosixify=false] - When true, output uses '/' separators for
+ *   cross-platform safety. Callers storing to version-controlled config files should opt in
+ *   by passing true. Default false preserves legacy platform-native separators for
+ *   backwards compatibility.
+ * @returns {string} Relative path if filePath is inside basePath, otherwise filePath itself.
+ *
+ * @example
+ * getRelativePathWithinBasePath('/users/john/collections/api', '/users/john/collections/api/files/payload.txt');
+ *  → "files/payload.txt"
+ *
+ * @example
+ * getRelativePathWithinBasePath('/users/john/collections/api', '/users/john/downloads/payload.txt');
+ *  → "/users/john/downloads/payload.txt"
+ *
+ * @example
+ * On Windows with posixify enabled
+ * getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api', 'C:\\Users\\John\\Collections\\Api\\files\\payload.txt', true);
+ *  → "files/payload.txt"
+ */
+const getRelativePathWithinBasePath = (basePath, filePath, shouldPosixify = false) => {
+  if (!basePath || !filePath) {
+    return filePath;
+  }
+
+  try {
+    const relativePath = getRelativePath(basePath, filePath, shouldPosixify);
+    const sep = shouldPosixify ? '/' : brunoPath.sep;
+
+    if (
+      !relativePath
+      || relativePath === '.'
+      || relativePath === '..'
+      || relativePath.startsWith(`..${sep}`)
+      || brunoPath.isAbsolute(relativePath)
+    ) {
+      return shouldPosixify ? posixify(filePath) : filePath;
+    }
+
+    return relativePath;
+  } catch (error) {
+    return shouldPosixify ? posixify(filePath) : filePath;
+  }
+};
+
 const normalizePath = (p) => {
   if (!p) return '';
   return p.replace(/\\/g, '/').replace(/\/+$/, '');
 };
 
 export default brunoPath;
-export { getRelativePath, getBasename, getAbsoluteFilePath, normalizePath };
+export { getRelativePath, getBasename, getAbsoluteFilePath, getRelativePathWithinBasePath, normalizePath };
diff --git a/packages/bruno-app/src/utils/common/path.spec.js b/packages/bruno-app/src/utils/common/path.spec.js
index 4df2d6606db..e283ff4751f 100644
--- a/packages/bruno-app/src/utils/common/path.spec.js
+++ b/packages/bruno-app/src/utils/common/path.spec.js
@@ -5,7 +5,8 @@ jest.mock('platform', () => ({
   }
 }));
 
-import { getRelativePath, getBasename, getAbsoluteFilePath } from './path';
+import path from 'path';
+import { getRelativePath, getBasename, getAbsoluteFilePath, getRelativePathWithinBasePath } from './path';
 
 describe('Path Utilities - Unix Platform', () => {
   describe('getRelativePath', () => {
@@ -25,6 +26,10 @@ describe('Path Utilities - Unix Platform', () => {
       expect(getRelativePath('/users/john/projects', '/users/john/projects/src/components')).toBe('src/components');
     });
 
+    it('should return ".." for direct parent directory', () => {
+      expect(getRelativePath('/users/john/projects', '/users/john')).toBe('..');
+    });
+
     it('should handle null/undefined inputs', () => {
       expect(getRelativePath(null, '/users/john/projects')).toBe('/users/john/projects');
       expect(getRelativePath(undefined, '/users/john/projects')).toBe('/users/john/projects');
@@ -113,6 +118,78 @@ describe('Path Utilities - Unix Platform', () => {
     });
   });
 
+  describe('getRelativePathWithinBasePath', () => {
+    it('should store in-collection files as relative paths', () => {
+      const result = getRelativePathWithinBasePath('/users/john/collections/api', '/users/john/collections/api/files/payload.txt');
+      expect(result).toBe('files/payload.txt');
+    });
+
+    it('should handle collection paths with trailing separators', () => {
+      const result = getRelativePathWithinBasePath('/users/john/collections/api/', '/users/john/collections/api/files/payload.txt');
+      expect(result).toBe('files/payload.txt');
+    });
+
+    it('should resolve dot segments before deciding whether a file is inside the collection', () => {
+      const result = getRelativePathWithinBasePath('/users/john/collections/api', '/users/john/collections/api/files/../payload.txt');
+      expect(result).toBe('payload.txt');
+    });
+
+    it('should keep paths that resolve outside the collection absolute', () => {
+      const filePath = '/users/john/collections/api/../payload.txt';
+      const result = getRelativePathWithinBasePath('/users/john/collections/api', filePath);
+      expect(result).toBe(filePath);
+    });
+
+    it('should keep outside collection paths absolute', () => {
+      const filePath = '/users/john/downloads/payload.txt';
+      const result = getRelativePathWithinBasePath('/users/john/collections/api', filePath);
+      expect(result).toBe(filePath);
+    });
+
+    it('should keep sibling prefix paths absolute', () => {
+      const filePath = '/users/john/collections/api-other/payload.txt';
+      const result = getRelativePathWithinBasePath('/users/john/collections/api', filePath);
+      expect(result).toBe(filePath);
+    });
+
+    it('should keep same-path values unchanged', () => {
+      const filePath = '/users/john/collections/api';
+      const result = getRelativePathWithinBasePath('/users/john/collections/api', filePath);
+      expect(result).toBe(filePath);
+    });
+
+    it('should store in-collection paths whose names begin with two dots as relative paths', () => {
+      const result = getRelativePathWithinBasePath('/users/john/collections/api', '/users/john/collections/api/..payload.txt');
+      expect(result).toBe('..payload.txt');
+    });
+
+    it('should keep the original file path when inputs are missing', () => {
+      expect(getRelativePathWithinBasePath('', '/users/john/downloads/payload.txt')).toBe('/users/john/downloads/payload.txt');
+      expect(getRelativePathWithinBasePath('/users/john/collections/api', '')).toBe('');
+    });
+
+    it('should treat relative collection path as cwd-relative when file path is absolute', () => {
+      const collectionPath = 'collections/api';
+      const filePath = path.resolve(collectionPath, 'files/payload.txt');
+      const result = getRelativePathWithinBasePath(collectionPath, filePath);
+      expect(result).toBe('files/payload.txt');
+    });
+
+    it('should treat relative file path as cwd-relative when collection path is absolute', () => {
+      const collectionPath = path.resolve('collections/api');
+      const filePath = 'collections/api/files/payload.txt';
+      const result = getRelativePathWithinBasePath(collectionPath, filePath);
+      expect(result).toBe('files/payload.txt');
+    });
+
+    it('should treat both relative paths as cwd-relative for containment checks', () => {
+      const collectionPath = 'collections/api';
+      const filePath = 'collections/api/files/payload.txt';
+      const result = getRelativePathWithinBasePath(collectionPath, filePath);
+      expect(result).toBe('files/payload.txt');
+    });
+  });
+
   describe('Edge cases', () => {
     it('should handle very long paths', () => {
       const longPath = '/users/john/projects/' + 'a'.repeat(100);
diff --git a/packages/bruno-app/src/utils/common/path.windows.spec.js b/packages/bruno-app/src/utils/common/path.windows.spec.js
index b94e5a49992..c11f921d6aa 100644
--- a/packages/bruno-app/src/utils/common/path.windows.spec.js
+++ b/packages/bruno-app/src/utils/common/path.windows.spec.js
@@ -5,7 +5,7 @@ jest.mock('platform', () => ({
   }
 }));
 
-import { getRelativePath, getBasename, getAbsoluteFilePath } from './path';
+import { getRelativePath, getBasename, getAbsoluteFilePath, getRelativePathWithinBasePath } from './path';
 
 describe('Path Utilities - Windows Platform', () => {
   describe('getRelativePath', () => {
@@ -25,6 +25,14 @@ describe('Path Utilities - Windows Platform', () => {
       expect(getRelativePath('C:\\Users\\John\\Projects', 'C:\\Users\\John\\Projects\\src\\components', false)).toBe('src\\components');
     });
 
+    it('should return ".." for direct parent directory', () => {
+      expect(getRelativePath('C:\\Users\\John\\Projects', 'C:\\Users\\John', false)).toBe('..');
+    });
+
+    it('should return an absolute path for cross-drive targets', () => {
+      expect(getRelativePath('C:\\Users\\John\\Projects', 'D:\\payload.txt', false)).toBe('D:\\payload.txt');
+    });
+
     describe('with posixify enabled', () => {
       it('should convert backslashes to forward slashes', () => {
         expect(getRelativePath('C:\\Users\\John\\Projects', 'C:\\Users\\John\\Projects\\App')).toBe('App');
@@ -181,6 +189,113 @@ describe('Path Utilities - Windows Platform', () => {
     });
   });
 
+  describe('getRelativePathWithinBasePath', () => {
+    it('should store in-collection files as Windows relative paths with mixed separators', () => {
+      const result = getRelativePathWithinBasePath('C:/Users/John/Collections/Api', 'C:\\Users\\John\\Collections\\Api\\files\\payload.txt');
+      expect(result).toBe('files\\payload.txt');
+    });
+
+    it('should store nested in-collection files as Windows relative paths', () => {
+      const result = getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api', 'C:\\Users\\John\\Collections\\Api\\folder\\payload.txt');
+      expect(result).toBe('folder\\payload.txt');
+    });
+
+    it('should handle collection paths with trailing separators', () => {
+      const result = getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api\\', 'C:\\Users\\John\\Collections\\Api\\folder\\payload.txt');
+      expect(result).toBe('folder\\payload.txt');
+    });
+
+    it('should handle case differences in Windows drive paths', () => {
+      const result = getRelativePathWithinBasePath('c:\\users\\john\\collections\\api', 'C:\\Users\\John\\Collections\\Api\\folder\\payload.txt');
+      expect(result).toBe('folder\\payload.txt');
+    });
+
+    it('should resolve dot segments before deciding whether a file is inside the collection', () => {
+      const result = getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api', 'C:\\Users\\John\\Collections\\Api\\folder\\..\\payload.txt');
+      expect(result).toBe('payload.txt');
+    });
+
+    it('should keep paths that resolve outside the collection absolute', () => {
+      const filePath = 'C:\\Users\\John\\Collections\\Api\\..\\payload.txt';
+      const result = getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api', filePath);
+      expect(result).toBe(filePath);
+    });
+
+    it('should keep sibling prefix paths absolute', () => {
+      const filePath = 'C:\\Users\\John\\Collections\\ApiOther\\payload.txt';
+      const result = getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api', filePath);
+      expect(result).toBe(filePath);
+    });
+
+    it('should keep outside collection paths absolute', () => {
+      const filePath = 'C:\\Users\\John\\Downloads\\payload.txt';
+      const result = getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api', filePath);
+      expect(result).toBe(filePath);
+    });
+
+    it('should keep cross-drive paths absolute', () => {
+      const filePath = 'D:\\payload.txt';
+      const result = getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api', filePath);
+      expect(result).toBe(filePath);
+    });
+
+    it('should keep same-path values unchanged', () => {
+      const filePath = 'C:\\Users\\John\\Collections\\Api';
+      const result = getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api', filePath);
+      expect(result).toBe(filePath);
+    });
+
+    it('should keep the original file path when inputs are missing', () => {
+      expect(getRelativePathWithinBasePath('', 'C:\\Users\\John\\Downloads\\payload.txt')).toBe('C:\\Users\\John\\Downloads\\payload.txt');
+      expect(getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api', '')).toBe('');
+    });
+
+    describe('mixed separators (posix base / win file)', () => {
+      it('inside → relative path with native separators (default)', () => {
+        const r = getRelativePathWithinBasePath('C:/Users/John/Collections/Api', 'C:\\Users\\John\\Collections\\Api\\files\\payload.txt');
+        expect(r).toBe('files\\payload.txt');
+      });
+
+      it('outside → returns original filePath unchanged (default)', () => {
+        const r = getRelativePathWithinBasePath('C:/Users/John/Collections/Api', 'C:\\Users\\John\\Downloads\\payload.txt');
+        expect(r).toBe('C:\\Users\\John\\Downloads\\payload.txt');
+      });
+
+      it('outside → posixified absolute fallback when posixify=true', () => {
+        const r = getRelativePathWithinBasePath('C:/Users/John/Collections/Api', 'C:\\Users\\John\\Downloads\\payload.txt', true);
+        expect(r).toBe('C:/Users/John/Downloads/payload.txt');
+      });
+
+      it('inside → posixified relative path when posixify=true', () => {
+        const r = getRelativePathWithinBasePath('C:/Users/John/Collections/Api', 'C:\\Users\\John\\Collections\\Api\\files\\payload.txt', true);
+        expect(r).toBe('files/payload.txt');
+      });
+    });
+
+    describe('mixed separators (win base / posix file)', () => {
+      it('inside → relative path with native separators (default)', () => {
+        const r = getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api', 'C:/Users/John/Collections/Api/files/payload.txt');
+        expect(r).toBe('files\\payload.txt');
+      });
+
+      it('outside → returns original filePath as-is (default)', () => {
+        const r = getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api', 'C:/Users/John/Downloads/payload.txt');
+        // filePath uses '/', returned as-is since shouldPosixify=false
+        expect(r).toBe('C:/Users/John/Downloads/payload.txt');
+      });
+
+      it('outside → posixified fallback when posixify=true', () => {
+        const r = getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api', 'C:/Users/John/Downloads/payload.txt', true);
+        expect(r).toBe('C:/Users/John/Downloads/payload.txt');
+      });
+
+      it('inside → posixified relative path when posixify=true', () => {
+        const r = getRelativePathWithinBasePath('C:\\Users\\John\\Collections\\Api', 'C:/Users/John/Collections/Api/files/payload.txt', true);
+        expect(r).toBe('files/payload.txt');
+      });
+    });
+  });
+
   describe('Cross-platform path handling', () => {
     describe('Windows fromPath with POSIX toPath', () => {
       it('should handle Windows fromPath with POSIX toPath in getAbsoluteFilePath', () => {
diff --git a/tests/collection/opencollection/multipart-file-path.spec.ts b/tests/collection/opencollection/multipart-file-path.spec.ts
new file mode 100644
index 00000000000..9e940aa9f60
--- /dev/null
+++ b/tests/collection/opencollection/multipart-file-path.spec.ts
@@ -0,0 +1,146 @@
+import { test, expect, closeElectronApp } from '../../../playwright';
+import {
+  addMultipartFileToLastRow,
+  openRequest,
+  removeFirstMultipartFile,
+  saveRequest,
+  selectRequestBodyMode,
+  selectRequestPaneTab
+} from '../../utils/page';
+import * as fs from 'fs';
+import * as path from 'path';
+
+const collectionName = 'RelativePathBug';
+const requestName = 'upload-payload';
+const relativePayloadPath = path.join('files', 'payload.json');
+
+const writeJson = async (filePath: string, value: unknown) => {
+  await fs.promises.writeFile(filePath, JSON.stringify(value, null, 2), 'utf-8');
+};
+
+const setupOpenCollection = async (collectionDir: string, userDataDir: string) => {
+  await fs.promises.mkdir(path.join(collectionDir, 'files'), { recursive: true });
+  await fs.promises.mkdir(userDataDir, { recursive: true });
+
+  await fs.promises.writeFile(
+    path.join(collectionDir, 'opencollection.yml'),
+    [
+      'opencollection: "1.0.0"',
+      'info:',
+      `  name: ${collectionName}`,
+      '  type: collection',
+      ''
+    ].join('\n'),
+    'utf-8'
+  );
+
+  await fs.promises.writeFile(
+    path.join(collectionDir, relativePayloadPath),
+    '{"ok":true}\n',
+    'utf-8'
+  );
+
+  await fs.promises.writeFile(
+    path.join(collectionDir, `${requestName}.yml`),
+    [
+      'info:',
+      `  name: ${requestName}`,
+      '  type: http',
+      '  seq: 1',
+      '',
+      'http:',
+      '  method: POST',
+      '  url: https://example.com/upload',
+      '',
+      'settings:',
+      '  encodeUrl: true',
+      '  timeout: 0',
+      '  followRedirects: true',
+      '  maxRedirects: 5',
+      ''
+    ].join('\n'),
+    'utf-8'
+  );
+
+  await writeJson(path.join(userDataDir, 'preferences.json'), {
+    lastOpenedCollections: [collectionDir],
+    preferences: {
+      onboarding: {
+        hasLaunchedBefore: true,
+        hasSeenWelcomeModal: true
+      }
+    }
+  });
+
+  await writeJson(path.join(userDataDir, 'collection-security.json'), {
+    collections: [
+      {
+        path: collectionDir,
+        securityConfig: {
+          jsSandboxMode: 'safe'
+        }
+      }
+    ]
+  });
+};
+
+const expectRequestFileToContainRelativePayload = async (requestFilePath: string, payloadPath: string) => {
+  await expect.poll(async () => fs.existsSync(requestFilePath)).toBe(true);
+  await expect.poll(async () => fs.promises.readFile(requestFilePath, 'utf-8')).toContain(` ${relativePayloadPath}\n`);
+  await expect.poll(async () => fs.promises.readFile(requestFilePath, 'utf-8')).not.toContain(payloadPath);
+};
+
+const expectRequestFileNotToContainPayload = async (requestFilePath: string, payloadPath: string) => {
+  await expect.poll(async () => fs.promises.readFile(requestFilePath, 'utf-8')).not.toContain(` ${relativePayloadPath}\n`);
+  await expect.poll(async () => fs.promises.readFile(requestFilePath, 'utf-8')).not.toContain(payloadPath);
+};
+
+test.describe('OpenCollection multipart file paths', () => {
+  test('keeps an in-collection multipart file relative after restart, OpenCollection edit, remove, and re-add', async ({
+    launchElectronApp,
+    createTmpDir
+  }) => {
+    const collectionDir = path.join(await createTmpDir('opencollection-multipart'), collectionName);
+    const userDataDir = await createTmpDir('opencollection-multipart-userdata');
+    const payloadPath = path.join(collectionDir, relativePayloadPath);
+    const requestFilePath = path.join(collectionDir, `${requestName}.yml`);
+
+    await setupOpenCollection(collectionDir, userDataDir);
+
+    let electronApp = await launchElectronApp({ userDataPath: userDataDir });
+    let page = await electronApp.firstWindow();
+    await page.locator('[data-app-state="loaded"]').waitFor({ timeout: 30000 });
+
+    await expect(page.locator('#sidebar-collection-name').filter({ hasText: collectionName })).toBeVisible();
+    await expect.poll(async () => fs.existsSync(requestFilePath), {
+      timeout: 15000
+    }).toBe(true);
+
+    await openRequest(page, collectionName, requestName, { persist: true });
+    await selectRequestBodyMode(page, 'Multipart Form');
+
+    await addMultipartFileToLastRow(page, electronApp, payloadPath);
+    await saveRequest(page);
+    await expectRequestFileToContainRelativePayload(requestFilePath, payloadPath);
+
+    await closeElectronApp(electronApp);
+    await fs.promises.appendFile(path.join(collectionDir, 'opencollection.yml'), '\n\n', 'utf-8');
+
+    electronApp = await launchElectronApp({ userDataPath: userDataDir });
+    page = await electronApp.firstWindow();
+    await page.locator('[data-app-state="loaded"]').waitFor({ timeout: 30000 });
+    await expect(page.locator('#sidebar-collection-name').filter({ hasText: collectionName })).toBeVisible();
+
+    await openRequest(page, collectionName, requestName, { persist: true });
+    await selectRequestPaneTab(page, 'Body');
+    await removeFirstMultipartFile(page);
+    await saveRequest(page);
+    await expectRequestFileNotToContainPayload(requestFilePath, payloadPath);
+
+    await addMultipartFileToLastRow(page, electronApp, payloadPath);
+    await saveRequest(page);
+
+    await expectRequestFileToContainRelativePayload(requestFilePath, payloadPath);
+    await closeElectronApp(electronApp);
+  });
+});
diff --git a/tests/utils/page/actions.ts b/tests/utils/page/actions.ts
index 873bd09b371..52fe7e6d66a 100644
--- a/tests/utils/page/actions.ts
+++ b/tests/utils/page/actions.ts
@@ -1,5 +1,6 @@
 import { test, expect, Page, ElectronApplication, waitForReadyPage as waitForReadyPageImpl } from '../../../playwright';
 import process from 'node:process';
+import * as path from 'path';
 import { buildCommonLocators, buildScriptErrorLocators } from './locators';
 
 type SandboxMode = 'safe' | 'developer';
@@ -995,6 +996,50 @@ const selectRequestPaneTab = async (page: Page, tabName: string) => {
   await selectPaneTab(page, '[data-testid="request-pane"] > .px-4', tabName);
 };
 
+const selectRequestBodyMode = async (page: Page, mode: string) => {
+  await test.step(`Select request body mode "${mode}"`, async () => {
+    await selectRequestPaneTab(page, 'Body');
+    const locators = buildCommonLocators(page);
+    await locators.request.bodyModeSelector().click();
+    await locators.dropdown.item(mode).click();
+  });
+};
+
+const mockBrowseFiles = async (electronApp: ElectronApplication, filePaths: string[]) => {
+  await electronApp.evaluate(({ dialog }, selectedPaths: string[]) => {
+    const originalShowOpenDialog = dialog.showOpenDialog;
+    dialog.showOpenDialog = async (...args) => {
+      dialog.showOpenDialog = originalShowOpenDialog;
+      return {
+        canceled: false,
+        filePaths: selectedPaths
+      };
+    };
+  }, filePaths);
+};
+
+const addMultipartFileToLastRow = async (page: Page, electronApp: ElectronApplication, filePath: string) => {
+  await test.step(`Add multipart file "${path.basename(filePath)}"`, async () => {
+    await mockBrowseFiles(electronApp, [filePath]);
+
+    const table = buildCommonLocators(page).table('editable-table');
+    const lastRow = table.allRows().last();
+
+    await expect(lastRow.locator('.upload-btn')).toBeVisible();
+    await lastRow.locator('.upload-btn').click();
+    await expect(lastRow.locator('.file-value-cell')).toContainText(path.basename(filePath));
+  });
+};
+
+const removeFirstMultipartFile = async (page: Page) => {
+  await test.step('Remove first multipart file', async () => {
+    const table = buildCommonLocators(page).table('editable-table');
+    await expect(table.allRows().locator('.file-value-cell').first()).toBeVisible();
+    await table.allRows().first().locator('.clear-file-btn').click();
+    await expect(table.allRows().first().locator('.upload-btn')).toBeVisible();
+  });
+};
+
 /**
  * Verify response contains specific text
  * @param page - The page object
@@ -1402,7 +1447,11 @@ export {
   getResponseBody,
   expectResponseContains,
   selectRequestPaneTab,
+  selectRequestBodyMode,
   selectResponsePaneTab,
+  mockBrowseFiles,
+  addMultipartFileToLastRow,
+  removeFirstMultipartFile,
   sendRequestAndWaitForResponse,
   switchResponseFormat,
   switchToPreviewTab,