well, recently I had my dad and his wife check-in under reservations I had made for them at two SPG properties, one in downtown toronto and one in PA, with their names nowhere to be found on the reservation and I never added them to the reservation. It was purely under my name with them checking in and using their credit card to pay for it and I was at home in NY collecting the points!!!

I still got the points posted from both stays although they checked in and used their own cards to pay!

So, in contrary to what people are writing, this has worked with two properties...I'm sure this isn't the norm though...