I recently had a guest who needed to receive a package while staying at my apartment. I was worried because if she addressed it to me, the post office would ask to see my ID to pick it up. If she addressed the package to herself, the post office wouldn’t deliver it to my address.
So I stopped by the post office to ask what we should do and it turned out to be very easy. Address the package to the person who’ll be picking up the package and can show ID. Then the second line should read “Chez [name of person whose name is on the mailbox]”, then the address on the lines below. In other words, “Chez” works just like “c/o” would in the U.S.
It’s not often there’s a simple answer in Paris!