I just read through the FAQ's. One states that you do not need to register each aircraft, that you will get an individual number (like an AMA number) to use on all of your aircraft.
It says there is no need to provide information about each specific model.
THEN, in the section about 'What if I sell my drone?' it says you should log in and update your information if you sell something. Update what? You didn't give them specifics about your 'drones' in the first place.
Somebody's not thinking clearly.