Firefox data recovery
Firefox data recovery
Exporting a whole FF profile:
How to Transfer a Firefox Profile to a New Computer | Firefox Support Forum | Mozilla Support
support.mozilla.org
"The file location is "%APPDATA%\Mozilla\Firefox\Profiles". Simply copy that, throw it on a flash drive, and then move it to the same location on the new machine."
From my perspective, Local was the latest update. Last week, it was instead of last October. So Local is it.
Since I do this all the time, if you have an existing Firefox install, delete the data that's already there and put the backup there so Firefox uses that instead of the other profile
AFAIK, there's no way to merge the data via this method