I have been MOH for two friends already and I can't decide who to choose to be my MOH. Of all my friends who would be in the wedding party, I'm closest to a girl who I wasn't MOH for. I'm closer to one of the MOHs than the other. I feel obligated to ask the two MOHs to be mine, even though I'm not closest to them. Is there some kind of etiquette when it comes to choosing MOHs?