I was actually schcked when I inquired with MS on the availability of an additional studio for a 5th family member, and the MS rep stated, its no problem we can just put 5 in a studio, as long as we provide the additional bedding needed.
A year ago, they were very strict when listing occupants not to exceed 4.
I think this issue must have been challenged by members, because the rules for occupancy have become more liberal for families of 5.
and not more than 5.