I don't know if you caught my post #19 in this thread. If not, please scroll up to it.

The Abound program will do what you're suggesting.

Owners of Marriott Vacation Club, Sheraton Vacation Club, and Westin Vacation Club resorts whose weeks are enrolled in the program, as well the owners of Club Trust Points (and apparently owners in a similar points program in Vistana Signature Experiences), will be able to log in to the same website or phone in to their Owner Service number and use a common points currency to book nights across all the brands, as well as booking other options.

There will still be other programs for historical reasons and to provide flexility to stay outside the Marriott-affiliated properties of Marriott Vacation Worldwide. But it's likely that many owners will rely solely on Abound.

The name of this topic -- Marriott Vacation Club branding/name change to “Abound by Marriott Vacations” -- is misleading and has caused some confusion. Marriott Vacation Club is not changing its name. Only the internal exchange program is changing its name as it encompasses more brands.

I agree with TerryK that timeshare programs have become very complicated. They began as something very straightforward. People could buy a specific unit at a specific resort for a specific week each year. The developer would typically sell the same unit to 51 buyers for one week each, setting aside a 52nd week for annual maintenance. Not very flexible, but very simple. Over time, in an effort to provide "unlimited" flexibility, timeshare systems have become quite complex, with a myriad of options. And with those options have come sorts or rules, limitations, deadlines, and such.