Maybe it's me but I need an explanation. Why does the cost per. person increase when you book 3 to a cabin. It seems to me that it should decrease(or at least remain the same) being that they will get additional money for that same cabin(especially when the third person is a child). Book 4 to a room and the price remains the same for the first two guest.
The cost per person shouldn't increase when adding a 3rd guest, unless they have to change the cabin to higher cost one that accommodates 3 guests.
When 4 people are in a cabin, the first 2 guests are full fare. The 3rd and 4th are less. We usually just divide it evenly among ourselves.