If I were you and you want the flexibility of the DC system, I would rescind the purchase of the points from Marriott, pay to enroll your existing Royal Palms week, and then simply rent whatever additional points you need here at VPE.  You'll save a tone of $$ and get to exactly where you want to be from a points perspective, while at the same time being able to rent extra points only in the years you need them, and not during the years you plan to travel to non MVC destinations.  Good luck!!