Talk about your boundaries before you make the move so that you both have what you need as a couple and as two individuals. It is so awesome that you are going to support them through what could be difficult times ahead I guess. So lovely
But there has to be an equal balancing of needs between everyone and you cannot talk about that too much. And after the move, keep talking. It will help if you and your wife have a united front when working out any areas of disagreement or whatever.. so talking things through together first is always nice.