Hi delmaracer, Firefox can't do it using built-in feature. The Restore feature first removes all the existing bookmarks, so that can't be used for merging. I have a page to convert the .jsonlz4 backup file to an importable HTML file. Importing is nondestructive, but causes massive duplication. You then would need to reorganize and deduplicate, which I don't think is efficient in Firefox. * Convert: https://www.jeffersonscher.com/ffu/bookbackreader.html * Import: [[Import Bookmarks from an HTML file]] * Example extension for de-duplicating: https://addons.mozilla.org/firefox/addon/bookmarks-organizer/ Since Internet Explorer can import a bookmarks.html file to Windows Favorites, if you find a good tool to deduplicate Favorites, that might do the job. At the end, you'll need to export back to bookmarks.html or use Firefox's feature to import from another browser (reads Favorites directly).