While I think it's ok sometimes to not feed the adult parents of the children invited to the party, I think if you have family coming you can't expect NOT to feed them. What are they supposed to do at the party? They're not bowling, they're not eating...they're just watching. I think i would have a small bowling party for the friends with cupcakes and drinks served, and then have a family get together later - even if it's just cake and ice cream and no meal. I would not be offended at not being invited to a child family member's bowling party, but I think I would feel a little put out going as an aunt and not eating nor bowling.
I feel differently about the parents of the kids there. THey are there to supervise their kids, so you don't have to feel obligated to feed them nor pay for them to bowl. The adult family members are different - they are not supervising, they are only coming to be with your DD.
At this age, I think it's perfectly acceptable to start splitting the parties - having a party with your child's friends, and then a gathering with family.
But I mostly feel that if you don't want to feed people, don't have a party at a meal time. I assume if I go to a party at 11 or 12 that they will be feeding me - after all, that is a meal time, and I'm skipping a meal in order to be there. However, if the party is at 3 or 4, I assume that it is cake only. This is how my mother taught me, since that's the way people used to do it. I realize that many parties these days have food no matter when it is. I've been to parties where there is pizza at 3 in the afternoon. But I think as a general rule you can avoid serving food if it's an afternoon party.
Bowling and cupcakes with the children, and a family gathering on a Sunday....that's what I would do.