57 Bel Air front seat back removal

Hi everybody! I am new to TriFiveChevys. Hoping that someone can help me out with the front seats in my son's 57 Bel Air sport coupe. We are doing a resto-mod on the car. Installing new upholstery foam and seat covers. The back seat was easy - the front seat not so much. To get the seat cover over the bottom (bench) we need to remove the seat backs. We can't figure out how to detach the inside of the seat - both seat backs are attached to a fitting that in turn is attached to the bench.

Any help or suggestions would be most appreciated.

You have to remove the clip that holds the seat back on a pin which is attached to the seat bottom first. This clip is on the outside lower portion of the seat; once that clip is removed, the seat back will slip off both the outer and inner pins...