Firefox sync rules

[kltpzyxmrm]

When you sync profiles, How does Firefox determine what material is added or removed?

I'm mostly concerned about sessions content. Does one profile take precedence over the other in so far as the direction in which the data moves, in an incremental of differential process? Is it just about the date? Or is it just a matter of pooling of all the data?

I have some older profiles with sessions I'd like to meld with my later profile, but I'm wondering what the outcome would be.

[kltpzyxmrm]

Should I have posted elsewhere, like Firefox Support? I'm disappointed that there was no response, even if it was just to say 'there are no known solutions to your inquiry", or maybe you should check in another particular support venue, so I wouldn't have to keep checking back here.

thanks

[BobbyPhoenix]

Sorry for the book, but I hope it helps.

I believe the fist session you sync will be the "master" sync. I've used sync for years, so I can't really remember the first time, but I've added several new instances over the years, and one recently. As soon as I enabled sync on the new machine, it synced everything (all my stuff from my old one came to the new one), but also things like default bookmarks from the new one that I deleted a long time ago from the old one, synced to the old one again. So I'm guessing whatever is different on each instance will be synced and merged.

The safest way I found is to download/backup your main profile you know you want to keep, and then if there is other stuff on the other instances you can enable sync to see how it works. If it messes things up you can always delete everything, and start over with your saved profile.

If you only want one version to keep on all instances (that's really what I prefer) then before enabling sync delete everything on the other instances (or uninstall Firefox along with all settings. This way you know you'll start clean/fresh), and then reinstall. Enable sync on the "master" instance, and then enable on the others (don't forget to delete default bookmarks if you don't want them synced), and you should have an exact copy on all. Of course this is with the belief you are syncing everything you can sync.

If you just want to sync specific things it's a bit different as I found out. Unlike Chrome where you can select what to sync on a fresh install, Firefox syncs all or nothing. Meaning if you have everything synced on your main profile, but don't want passwords synced on a new one, you have to be quick to uncheck passwords from sync as soon as you enable it since you don't get a prompt to choose what you want. Whatever is checked to sync on others will automatically be synced to new ones. If you're quick enough to uncheck things you'll be good as it takes a few seconds for sync to actually start syncing once you enable it.