End the waitlist. If presented with this problem set and myriad solutions, that will be the solution that Wyndham chooses. So watch what you wish for.
Ending the waitlist would mean the end of the 7-day minimum at 13 months (not that it means much as it is, but some owners think it does).
With no waitlist, any owner could reserve 7 days in a 3 bedroom at West Yellowstone . 4 days later, cancel the 7-day reservation, book a new 7-day reservation using a second account, and use a third account to rebook the desired 4-days from the first reservation as a stand alone reservation. 4 days later, cancel the new 7-day reservation, book a new 7-day reservation using the first account, because it is beyond the 48-hour restriction modifying the reservation in the first account, and rebook the desired 4-days as a stand alone reservation using the second account.
Book all the 3 bedroom units at West Yellowstone for rolling 7-day reservations beginning mid-May when there is no demand at 13 months, and you are a megarenter in business for the entire summer. Owners will have no chance to reserve a 3 bedroom at West Yellowstone all summer, or Coachella music festival, or Kihei 2 and 3 bedroom units for Christmas and New Years.
Get rid of the waitlist and might as well just hand the WorldMark system keys to the megarenters. It will be over for owners who use the waitlist to get something resembling a fair chance.
If the megarenter had to put all these 3-4 days reservations in the name of the guest who would be checking-in 13 months later, they could not make these reservations, because they would not know the names to attach to the reservation. A no name change on 12-13 month reservations would mostly end the megarenter problem. The owner or guest listed when the reservation is booked at 13 months uses the reservation, or it is cancelled and goes to the waitlist. If there is no waitlist, then we are back to where megarenters own WorldMark.
btw - there are many excellent WorldMark vacations available for family reunions within a 12-months booking window. Also, many family reunions in WorldMark Hawaii and other difficult to reserve resorts have been put together using the waitlist, but if there is no waitlist ...