If there s only one legal adult and three others aren t, how do I book two separate hotel rooms without an adult in the other?

You can book 2 rooms in the adult's name, and have the adult check in for both. But the hotel can deny a room if you can't prove that there is an adult staying in it. There generally has to be an adult checked into and staying in each room. There are sometimes exceptions made for school trips, families traveling together, etc - but not for a group of teenagers traveling alone together.

How else would you do this, a magic spell?