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.
Wow! Many thanks for breathing some new life into the game. Having brought the amount of theatrical stuff down to a level I can actually cope with, I may consider re-entering the fray...
It's also just become clear how difficult Small Hypearthquakes is to finish...