Fiance and I are young, as in, just finishing college. We do not have much money. The guest list is already large, so adding kids would be too expensive. My side has a lot of children, including my 7 and 3 year old sisters, and my 5 year old nephew/godson. FI's side has only 2 kids -well behaved 8 year old twins, whose parents live a few states away. The parents(FI's aunt/uncle) and some of his side are angry about the twins and think we should make an exception, even suggesting they be ring bearer/flower girl simply because my fiance and his sister were in their wedding. If we had ring-bearer/flower girl, they would be my direct child-siblings anyway, not cousins. They say "who will watch the kids? We live far. The kids were excited to come. We can't come unless they come." The wedding is almost a year away, so we gave plenty notice. I don't want to be unfair to anyone, so its a firm 18 rule no exceptions, even for my very young siblings/godson (who are very badly behaved anyway).