It is possible to put 3 people in a triple or quad balcony cabin....but not in a sofa bed! If you want a sofa bed you will have to upgrade to a mini suite...which is not a bad idea because of the extra room you will get in the cabin (as well as a somewhat larger bathroom)! We had 3 adults in a mini suite on the Emerald Princess (sister to Ruby Princess) and it worked very well. I think 3 adults in a regular balcony cabin would be very cramped especially with a roll away bed....if I had to do it I would use the existing bunk bed!
I agree with Beryl.. either a Triple or Quad room, or a Mini-Suite..Our Best Buds for cruising do this on the occasion with their 16 year old DD ..she is a slender thing but it still does get smooshy..she sleeps in the Queen size Sofa fold out bed in the Mini-suite.. but as for a regular balcony..it's a no-no unless it's a true designated Triple or Quad.. it's the only way to "add a 3rd passenger".. to the stateroom..Happy Cruising!! Joanne
A couple of years ago a friend on mine decided to take his mother along with he and his wife on Caribbean Princess with 3 other couples including The Boss and I. He was going to get a mini-suite for the three of them. This didn't seem like a good idea to me. I talked him into booking a cat BB balcony on Caribe deck like the rest of us and booking an inside cabin across the hall for his mother. This alternative was $27 cheaper than 3 in a mini-suite.