Hello Everyone, need some advice

There are 3 of us traveling together in a couple of weeks. Our destination seems to be sold out for the one night we need hotel rooms. Hilton, Marriott, Hyatt, Holiday Inn, SPG, you name it - it's all gone. There are a few no-name hotels, but in inconvenient locations (outskirts), but we would like to stick close together since we'll probably share a rental car and have a dinner togehter.

here is the dilemma - there are 3 of us:
1 x diamond
1 x gold (me)
1 x silver

We tried to use the diamond guarantee at one HH property, but it seems like that's only for one room and the front desk canceled the other ones.

What would be your advice? Is it allowed by Diamond Privileges to book 3 single reservations at 3 different Hilton properties on the same day? It would be 2 Hamptons and 1 Hilton? They are all pretty close together.

If we do make 3 reservations, we have the challenge of the diamond member going into each hotel and changing the name on the reservation, which I am sure front desk will frown upon....

Anyway, your advice and experience would be very helpful.
P.S. Did a search (non-google) and did not see anything good.