We "rented" points from a DVC member for a studio at the Boardwalk villas, and now are wondering if we shouldn't have gone with the 1-bedroom. My question then, is it possible to upgrade at check-in and pay the difference?
Sorry, no option to upgrade with either points or cash.
Depending on how far out your trip is, and if the member has sufficient points, you could ask him to try and rent a 1BR for you and then cancel the studio.