I have booked award rooms for 3 with no problem (in London among other places). They have usually brought in a roll away or given a suite/sofa bed room, ect...
I would not chance it as 3 of you may have to sleep in 2 twin beds or 1 "double" bed. When I have asked they have always been more than helpful.

Also, if you want bennies, you have to be honest up front. Just my 2 cents.