Each game fork has its own rules. Additional forks may be possible if the particular game would allow it at the time. Reunifications must be legal in all affected forks.
Ohhhh, so that's what this game is! I thought it was just a two-stranded MC game. Brilliant stuff, everyone. I particularly like the reunifying aspect. I may make a move at some point in the future (I take it's not going to go away too soon) but not at all imminently. (It's a bit disturbing that I missed Acre Street whilst away from MC, isn't it?)