It is not adding additional guests. I booked a cabin and didn't have the legal name of the other person. So I was listed as the first guest, and my cabin mate was listed as "to be named". I went in later to put in the name. The cabin was booked for two right from the beginning. I think it would be possible to book a cabin for 4, for example, putting in the one name, and listing the other three as "to be named" but still booking it for 4 and paying the deposit for 4.