Originally Posted by
windowontheAside
If your underlying ticket is a WT+ cash fare, I don't think you can UuA to F. I thought you could only UuA one class?
I believe that's true but is not what the OP is trying to do.
As I read it, they booked CW out and WTP back. They UuA'd the return leg to CW at the time of booking and there is now availability to UuA the outbound leg into F, having been originally in CW