Seats into bed

The seats have an additional "lid" to the box section. This second lid is hinged so it opens out to make the bed wider. A supporting “leg/support” rests against the seats and can simply be placed on the floor to support the bed sections when they hinge over.
The seat/bed sections are in 3 parts along the length. This makes it easier to open/extend the seat sections. It would be tricky to lift the whole length of the seat lids with the cushions on if it was all 1 section.