If they want to book
DVC resort with rented points find a member who wants to make a points transfer to rent from; they will transfer the points to your membership account and then you can make and handle the reservation for your friends with Member Services just as you would with your own points. Just be sure the points will be valid for use during the dates of their trip and most important get enough points transferred over because you are allowed only 1 transfer per use year so you don't want to find that you're short on the amount of points that would be needed after the transfer has taken place.
Good luck & you're a good friend trying to assist that family