I know parents of children involved in the ceremony are invited to the Rehearsal Dinner, but what about adult siblings? My 11-year-old cousin is supposed to escort my stepmother down the aisle, and so we're inviting him to the rehearsal to get the hang of it before the big day. Obviously, we're inviting his parents. But what about his adult brother and brother's live-in girlfriend? We're not inviting any other cousins except those who're involved in the ceremony in some way.