The diamond benefit would extend to this reservation for you and your wife since you're a guest of the room - there's a bunch of threads on this. No different than if you are renting it yourself. You can do the search. Usually people call or send a note to the hotel to mention this or tell them at checkin.

As for getting the stay/night credits to your name - that might be a little YMMV type situation as you suggested. I think your odds are lower, but you can always try.