Maybe you could just both own the swamp so you can both build in it? If Yqt just wants to finish a building, you could probably just negotiate it with Jorster and then he could be the 'main' manager there, building without the need to ask Yqt unless modifying Yqt's developments. That would just be my idea. More cooperative areas might be fun and then you both still have plenty of area where you can build without interference.
I'm fine with a region there so the negotiation should be between Yqt and Jorster.