The second post was a good suggestion, and that's actually what I do. My girlfriend and I both travel a lot for work. I do Marriott / SPG, and she does Hilton. Every now and then we'll hit a situation where she'll either need to stay at Marriott/SPG or I'll need to stay at Hilton. We book the reservation for ourselves and then call to get the other person added to the rez. Has worked every time.