I realize that there isn't anything built in to Advanced Forum, but I was hoping someone can tell me a way to split threads (and merge too, actually).

But I get that there may not be. Just hoping.

Comments

I am not aware of anything. Comment Mover looks like it might be getting some love in D7 but that's still early. I'll leave this active for a bit in case someone else has an idea.

I have had to solve this issue for a project I am working on. (Well split, not merge)

I have created a sandbox module with the solution.
http://drupal.org/sandbox/JeremyFrench/1838272

I don't know if this is something that would fit and be merged with with advanced forums, or if it should stay as a module in its own right.

I'm happy to produce a patch if you would like the code merged.

Finally had a moment to give this a go and it seems to work well. I've only split one thread on my live site so far. But thanks for this. It will be a big help.