Most hotels would see that and assume that you wanted two beds...so it is strange that they would even put you in a single bed room. But, evidently your rewards profile must trump the information in the reservation. Do many people regularly have four people to one bed? I think the easiest thing to do is to call beforehand. I don't know many families that would go through the inconvenience of being assigned a room that didn't fit them for a measly $100 credit. I think the parents probably paid their dues just traveling with the kids in the first place.