When you set up the waitlist, it will give you the option to replace an existing reservation,
If you want to set up a waitlist to replace some nights of the reservation, but not all of them, then you have to call MS for that!.
If want to change an existing reservation, you can now modify it online, search for what you want, and book the new resort if available. if not, just close out,
Its a great option because it doesn’t require the original reservation booked to be canceled first. Years ago, even when we could only call MS, there were times that one could lose it when the switch happend,