You'll really need to call. I recently made an online exchange for a resort in an overdeveloped destination (Branson) for an off season week (Dec. 4th) thinking there would be more than 1 unit available.
I was wrong. I ended up making one trade for a two bedroom unit and then had to make two additional exchanges for a 1 bedroom and a studio unit to get two 2 bedroom units in the same resort. After each exchange the 1 and 2 bedroom unit availability vanished with only studio units showing for that particular resort on that particular exchange date. Who'd have thought?
My problem was I was attempting to trade up, using two 1 bedroom units and a studio unit to get two 2 bedroom units. I felt if I called I might not be able to trade up. Next time I call and see what the exchange company will let me do before just jumping in online.