I have often wondered how to do this. If I wanted to "gift" a points stay to someone else, while keeping, say, the 5th night free perk. I had not really got much further than the idea of setting up a HH account for that other person and then crediting that account with the requisite points.

I agree that Hilton is good with the second registered guest arriving first situation. This is a very useful benefit say if both guests are expected at different times (which could be for multiple reasons such as traveling to the city from different locations).