You will never get definitive information from Diamond. Answers always depend on who you take with. One persons says one thing, another says something else: it's the Diamond way.
Here is what's posted on the resort pages for each of the three locations:
Tremblant
No information about the resort fee
Blue Mountain
"-A resort fee of $21.95 CAD plus tax per night will be added to the reservation if the owner or member of THE Club® is checking in on a rental reservation."
Sandestin
"When checking in:
"- Hotel Guests: A photo identification, credit card for $100 security deposit and a daily $21.95 plus tax resort fee will be required (cash is not an acceptable form of deposit).
"- Member Points Booking: Photo Identification and credit card for security deposit will need to be provided at check-in. Resort fees* will be waived when staying on your member point reservations. A resort fee of $21.95 plus tax per night will be added to the reservation if the member of Embarc™ is checking in on a rental reservation."
The non-Embarc resorts that Diamond manages state the resort for "Hotel Guests and Exchange Reservation." Maybe the Embarc resorts are an exception and they don't charge exchange guests (so "Exchange Reservation" is not in the text). Maybe the person writing the web page made a mistake by leaving out "Exchange Reservation". Clearly a mistake was make by the Diamond employee who wrote the Blue Mountain text, because Embarc members are not member of THE Club.
Good luck, but even if you get the correct information, you will not know it is correct. Diamond is sorry company.