A month or two ago I called the Diamond line to get an award reservation in Florida for next March, put in my sister in law's name. They said the only way they could do it is put both her's and my, names on it.
We discussed this, as we need the sister in law to be able to check in, as we might arrive later at the same hotel- we have another room booked for DW and myself.
I also asked to have the record sure the reservation was linked to me, so Diamond benefits and upgrades would flow. Notes were made. Hopefully this will all play out.