The only exception is if you are a parent with underage children and you need to book a second room for them. Then you can book a second room for the children. But otherwise, the rules state that you have to have one annual passholder registered in each room.
We are 5...2 adults and kids 17, 14 and 10 and would like the second room for the older 2 as two rooms means two baths...would this qualify. ie putting the older two kids in one room and us two with the youngest in another??