I called/emailed a couple of the DTD Hotels were are considering for our January trip with that very question.
HRP and the Grosvernor, both said you are able to purchase UPHs at the Disney owned-store located in their lobby's. The hotel itself does not sell the passes.
I even had my call transfered to the
Disney store in the HRP, and spoke with the manager of that store who assured me I would be able to purchase, and use the DC discount, in the store as it was Disney owned and she was employed by Disney.
I emailed the Courtyard by Marriott with several quesitons but omitted that particualr question so I can't be positive about that property. However, if you are in doubt you can call the hotel directly and ask to speak with someone in the Disney store.
This is the first time we are planning to stay in a DTD hotel, we usually stay at a Disney resort, so it is VERY important to us to be able to purchase UHPs wherever we decide to stay.
Figment