it's an all wood chair that needs a very fancy solution. Several pics are now up.
Using Rowley hook strip HS200/4W screwed to underside of wood seat so that the hook faces chair perimeter and the right angled surface is wedge cut with tin snips to mold the curve.
look under Embassy chair.
I am preparing a sample for the estimate submission, there are only four chairs to do.
I must also make a set of cushions to present for estimate.