I've found the best thing if you want to be sure is to call and say you'll be arriving later and that you'd like all the perks and everything to go to whoever checks in first. It's not like they'll stop your parents later and say 'where's your son?' once the room is paid for and they've already settled in. In theory, they could always retort 'oh he had to cancel last minute.' Hyatt shouldn't care once the room is 'paid for' with money or whatever else.
