OP- thanks for all the replies. As some posters have said they themselves will pay for their kids expenses when their kid goes someplace, as have I. So that is why I came and asked, because I wasn't sure what the proper protocol is.
When DD's friends relatives take her place, I always give her money for spending, treats for both girls if they go out of town and the relatives usually drive, so there isn't the big expense of the plane and they own a beach house, so there is no extra money spent there.
DD and I have been going on vacations since she was 4 and this year will be our 4th
DCL cruise. She does love the clubs, but we do hang out as well.
I started thinking about the paper work that would be involved ,as I am a single mom with custody and I am crazy paranoid about remembering to take it, let alone someone's elses paperwork.
So, the DM and I were talking: her dd has never been on a plane or a ship. I decided to change my vacation a little bit, as in go on shorter DCL cruise in December and we will go to WDW for a mini trip the weekend of Halloween.
Her DM will pay for the airfare-which she offered before I said anything and the DD will save money for souvies and I pay for food, SW ticket and hotel. We are all going to do the give a day get a day-so that will be one less expense, 1 day at SW and they get to trick or treat at WDW.
Thanks again.