Wow, that's a tough one! I can see both sides of it.
I've actually watched that event on tv.
I like the option of the group paying for the team and chaperones, but having it open enough for family to come also. If I couldn't raise enough money to take my other child, I would feel bad, but at the same time the only reason my one child would be going was because she was part of a team.
My brother was able to travel to Scotland with the HS for a music festival. My sister has always wanted to visit Scotland. If she could raise the money on her own, they would let her travel with the group, but it was on her to raise the money, just as my brother had to raise his own portion. My brother was able to raise his amount, my sister was not. She did NOT visit Scotland.
The only thing with family coming along also will be the rooms. Would you all stay at a Value Resort? The # of rooms needed would differ drastically. The number of chaperones needed would change drastically.
Say that Amy has one girl on the team, but three kids in the family. If just she and the cheerleader attend, they can share a room with another mom and daughter. If all three girls attend, Amy would want to share a room with all three which means you would need another room for the mom and daughter that now can't share.
One thing to do would be to determine the maximum number of people that WOULD attend if they could. Contact Disney for a group price and figure out a base price per-person. At 10-11y old, if you did the dinning plan, the girls would be considered 'adults'. You could also get a group price per-person for if JUST the team and chaperones went. You would need a minimum of 1 parent to 3 girls. Its also possible that Disney would give one price for the team and chaperones and another for regular family. Once you have those #s, the parents can decide how to go forward. It would have to be a binding contract which means no one family backing out except for a few lean circumstances.
All money raised during the fundraiser if needed, should be deamed team money and in a team account. Not in any one parent's account. Once money is raised/turned in, if the girl cannot attend, the money she donated stays with the team.
What about travleing there? Would you fly? Charter bus? Parents caravan?
If you rent a charter bus, I believe you would be expected to cover the room expense for the driver.
Good luck, I hope they get to go.