The Hilton terms and conditions say:
Many hotels would grant the benefits to your wife in this situation, but she isn't entitled to them. If she herself is gold or diamond then that's a different story.
Otherwise you could book a room in your name and put anyone in the world as the second guest, and they could get diamond benefits without you ever turning up.
can’t they just charge the room, but waive it after the primary guest (diamond status) turns up?