Teams: FC Barcelona, First Vienna FC 1894
Yes, of course it's possible. Either the FMs of the forum where the threads are in or CMs and higher can move those threads.
I don't know if it makes much sense to move every single historical thread, but if there are some where you feel you want to continue the discussion but in this new forum, then it can be a good idea.
If you tell me which threads, I can move them for you.
I'm not normally a praying man, but if you're up there, please save me, Superman.