I've read a few cases of people with hacked accounts getting their points redeemed for China/HK stays. (Not just Marriott...more of a general thing.) So anything regarding different names on reservations, I'd play by the book and call Marriott directly ahead of time.

It might take them out of the upgrade pool but as a Gold you're not talking about a huge upgrade anyway.

Same last name usually isn't an issue....I've had my wife check-in lots of stays with the same credit card in my file with Marriott. But in HK I would not assume this will work.