Earlier thread: https://support.mozilla.org/questions/1200279 My answer: I don't know, but anything is possible when doing a two-way sync. ---- Do you need to restore an earlier set of bookmarks from backup? See: [[Restore bookmarks from backup or move them to another computer]]. If you do not want to wipe the current set, you can convert a backup file to an HTML format for importing (importing is additive and causes duplicates, but sometimes that is the lesser of two evils). It would be a matter of dragging a backup file onto this tool: https://www.jeffersonscher.com/res/bookbackreader.html To find the backup files: Open your current Firefox settings (AKA Firefox profile) folder using either * "3-bar" menu button > "?" button > Troubleshooting Information * (menu bar) Help > Troubleshooting Information * type or paste about:support in the address bar and press Enter In the first table on the page, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer. Then double-click into the '''bookmarkbackups''' folder.