Snooped around in the script file for region trading, changed some values, and found out how to force anyone to give any province to you (except if they have a single settlement) and the other way around.

I personally use it to give regions to factions that are about to die (I personally hate the world getting dominated by a couple of factions and every other faction dying off, in Rome I & Medieval II you could very easily prevent factions from dying through usage of console commands and the force diplomacy script, which was a godsend).

If anyone wants the file I guess I could upload it as a mod or just link it here, I'm just not sure if anyone even wants that ability so I am asking here before I do that effort.