Crew quarters are fully automated.
You tell the designer how long you want the ship to operate for and it assigns and robes crew quarters as necessary.
It accounts for if you grow or reduce the size of the ship, if you add or lower crew requirements and it auto adds in living quarters for your parasite crews when you add hangars.
There's no reason to add or remove crew quarters manually indeed you cannot even do so.
Edit: Ninja'd.
See above ^^