So…Long time…
Didn’t forget y’all. It just really took nearly six weeks to finally get the situation resolved.
During that time, I dealt with six different people. Three of those were from the U.S, by email, and another three from the UK (This involved emails and three separate international phone-calls…to three different customer service guys).
It initially took about ten days to get the first email answered, after which it took an average of five days to receive replies to my replies.
Nobody seemed to know the answer to the question of the possibility of grouping licenses together, in one sale. But after this back-and-forth (Like I said, for nearly six weeks) they eventually let me know that there are no transfer fees at all - Neither for the main program nor the expansions.
Fortunately, the buyer (Pebble) was extremely patient, and so eventually they ended up with everything they were after 
So…there it is
Edited to add: I should make it clear that the last guy (UK) who got on the help-train really did stick with me to get it all sorted out. Not only that, but apparently the whole affair has exposed some shortcomings in their understanding of these processes. I was also told that going forward this will be much clearer to support staff, regardless of location.
In the end, I guess I we were the guinea-pigs for this particular test, and anyone else who decides to sell will have a much easier time of it 