Due to the flexibility of
DVC, the types of rooms that members are getting, the length of their stays, and their check-in/check-out dates all heavily impact room scheduling.
Since DVC resorts by design are meant to be at 100% occupancy, being able to keep the same room (vacate the Studio portion and keep the 1-B/R portion) would depend on who else is checking-in that day,what type of villa they want, etc.
Let's say your villa numbers are #100/101 (for the 1-B/R portion and the attached Studio)
Suppose someone else checking in wants a 2-B/R. Meanwhile there's another 1-B/R somewhere else being vacated that same day, (call it villa #200), but the Studio portion (villa #201) is occupied by a different member who is not checking out, thus that villa is not yet available as a 2-B/R unit.
So to accommodate the new 2-B/R check-in, you would have to vacate (#100/101) and move to the 1-B/R unit (#200) that was being vacated by the other member. The new check-in would then get villa #100/101.
Now, the other situation would be if on the day you want to change, the new check-in members are (1) a member with a 1-B/R villa and (2) a different member with a Studio. In this case the new 1-B/R checkin could get villa #200 and the new Studio Check-in could get villa #101, and you could remain in villa #100.
Does it all make sense?
So whether you have to move or not all depends on the comings and goings of other members.