Have you already made the room reservation? If so, see if the same room in the same hotel allows a "pretend" reservation for 4 people. If so, call Hilton and ask if there is a rate change for more than 2 people in the room. If no change, ask them to put it in the record as 4 people. If there is a rate change and it's acceptable to you, go ahead and change it. I have often made award reservations (which are supposed to be for 2 people only), for 3 people, by calling HH. What Hotel are you booked into? I don't think there are many twin beded rooms in NYC Hiltons.