Back when you still made dining reservations by phone, I wanted to make a Crystal Palace ressie for my daughter and 4 friends (all age 16) who were going to WDW on a school music trip. The cast member was a bit reluctant but was OK with it when I gave a credit card number for them to charge in case there was a problem. We figured out the cost of meal, tax, and tip to the nearest dollar and told the parents that each girl would need that much cash, and everything worked out fine. You might want to call Guest Relations ahead of time and give them a heads up to make sure everything will run smoothly.