You can get a placeholder for your friend under their name even if your name is not on their reservation. If you are getting 2 placeholders (one for you and one for your friend), both MUST be used on the same sailing.
I did this before and made the reservation under my mom’s name and another one for me. Had no problem.
Another time was supposed to be for a friend but they were unsure. I ended up booking the placeholder under my name for the first room and DH for the second. That way we could use the second room for whoever wants to go with us and will just switch people around. If I would have made it under my friend’s name and they cancel, I lose the placeholder on the 2nd room. You cannot change the lead name on a reservation.
Hope this helps.