I took it apart...
I cut one of the side rails and cut the foot board area in half.
These are the parts I kept to use.
I attached the new sides using screws and wood glue.
I found some scrap foam (never know when you will need a small piece!) and covered it with the fabric of my daughters choice. For this cushion, you could sew it, but I just used my hot glue gun.
A perfect fit!