If there was a leak or something in the bathroom that was joined with their bedroom that's a possibility. My two stepsons use the bathroom connected to our bedroom because we had the house leveled and it made a pipe connected to the toilet start leaking, we can't fix it until the house settles in three weeks
The mattress could be in the master bedroom because HC was scared to sleep in her own room. (i'll use my house as an example again) one of my step sons had strep throat and stayed with his dad while they other one came to our house so he wouldn't get sick. They share a room (like HC and JR did) but when our oldest was with us he was scared to sleep in the room by himself so we took his mattress off his bed and put it in our floor for him to sleep on while he was there. I'm 21 and my fiancee is 26, so we're young but if he's scared neither one of us are going to leave him in a room by himself to be scared.
IMO
I agree about HC not wanting to sleep in her own room, i am not disputing that, but RC had to move to this MH b/c the children each needed a room of their own, per DCF. We know HC was scared of the dark.
As far as the bathroom, i have not heard anything about that MB bathroom being broken. Until i do, i will look at it as another inconsistancy from MC.