I realize that the DDP must be for the length of stay and that you must buy for everyone staying the room. However, is the DDP added to everyone's key or pass? Must you eat together to use the DDP or can me and the wife eat somewhere else than the kids (both over 18) at the same time?
Make sure that they know what their DDP credit limit is or you might find out that they used your points.
I remember a post last year where a Uncle thought that all of the points were his. The member found out the hard way when they went to pay for a meal and didn't have any credits left.
They got really upset and assumed that Disney had made the error. When they got back to the resort they complained to the Manager who traced the credit usage to two KTTW cards.
The Uncle thought that the DDP was the best deal ever, a endless supply of food.