You cant be in different cabins on the same booking and you can’t upgrade only one person on a booking - although it’s possible if you split booking first. As the OP noted he was in CW originally and the parents were in WT they can’t have been on the same booking to start with. All three would have had to be booked in to WT to start with if on the same booking so that’s quite some upgrade from WT to F.

anyway, it was just a question as I was curious.

EDIT: and now I am on my iPad rather than my phone I note it’s the OP’s first time posting, so welcome to FT!