ok no problem, thanks for responding, Laz
For the record, I am speculating here. It is entirely possible that Welder knows of a simple way to make this work, and if he does he is of course free to correct me. But as far as I can tell it's not really doable, at least not without a lot of work.
Someone earlier mentioned the more viable possibility, which is using the redirect system.
When there was disagreement over where 3CM belonged, it ended up being put in both forums, where the actual thread was in one forum and the other thread was a redirect leading to the actual thread. IDK how bumping interacted with that.
I don't know that opening up the redirect system to the public would be a good idea either, but it shold at least be more feasible than using the annoucement system, and at the very least gobos could set up redirects for people at request if it was something the community wanted and the thread was on-topic in both sections.
I think its a good idea, personally.
It might be possible to allow people to move their own threads, but as far as I know the redirect system doesn't bump with new posts. Still, may be better than nothing. I'll bring it up with the other mods.