I am usually asked for photo ID when using FFN's. The original poster is right to assert he will have to check in anyone "using" them, since they will technically be the poster.

As a message to the original poster, if you have a destination or date in mind I would suggest you call back and specifically ask for the booking, especially if you can give any flexibility. When I have called the Diamond line and asked for a specific hotel and given the agent room to look for open dates, they just started looking for availability, or rolled through dates I suggested till they could find a match. Have been indirectly extended more than once that way without even discussing an "extension." If your date is firm and there are multiple Hyatt's in the area it has also worked for me to accept a different hotel.