Very nice for you
I live in a two bedroom flat, with my disabled twelve year old daughter, as a full time working single parent.
when my eldest daughter comes to stay they share - when they lived together they had bunks, in fact I'm sorry to say that I don't see anything unreasonable whatsoever about two young teenagers having bunk beds, and I would suggest that there's a shed load of parents on this forum whose teenage kids share a room, and who cannot afford anything bigger, because they're paying their own rent or mortgage.
I pay my own rent - apparently we're paying yours as well!
If someone offered me another bedroom for sixteen quid a week, I'd think it was a 'king bargain, I could use it to keep my bikes in.
Sorry, but this all seems eminently sensible. If "we" are paying people's housing benefit we should be paying for what they need not what they just fancy - "to each according to their need" as someone famous once said.