I would think that you would have to show it paid off to change the ownership. That said, it probably shows the lien holder as owner anyway. If you wanted to take it over (be aware that as Greg said, it has little or no actual monetary value), you may be able to chance the name on the note with the lender. Depending on your responsibility with your grandmother, just take over the payments and have her book a week's use this year. Send a bill of sale to the lender showing her as seller, you as buyer,(notarized) and when the note is paid off it can be put into your name(s) in the normal course of deeding it out of the lien holder's name. It should be able to be done for little more than the cost the resort charges to do the transfer of ownership.
Jim