C.W.
As a mom of three I never take all my children to a party unless all 3 were invited. I just 1 is invited that is the only one that I take to the party. If my husband can't watch the other children then we just can't make it. I understand that is just me. I think I would just put on the invite that siblings are welcome at parents expense. Places that don't really have limitations is always the best bet for bday parties imo.