You must pay with a seapass card, but your daughter's friends seapasses don't have to be linked to your account. Set them up as separate so they get their own bill. Then, they can use their Visa card to pay off their charges at Guest Services before the end of the cruise. However, these might need to be setup as cash accounts. Not sure if they will link a pre-paid card during the cruise. You could also make their accounts separate, but give your card for all of them. That way you would get separately itemized bills for each person at the end. Then you can just give the parents their daughter's bills for reimbursement.