Hello, This is not currently possible with Firefox Sync. But there is an open bug where others have requested it. See here: [https://bugzilla.mozilla.org/show_bug.cgi?id=444284 BugID 444284]. You can add your support for this request by voting for the bug in bugzilla. You can also keep an eye (and get email updates) on the bug to follow any new developments. Hopefully this feature will be added to Firefox soon. I hope that helps. I hope that helps.