This thread has me confused. "side clamping" feet are basically like the low shank feet.... right?
The Kenmore 117- 959 is a rotary hook machine. Rotary means the bobbin hook rotates, oscillating means the hook turns half way forward then backs up then repeats very fast.
Singer 15-91s are oscillating hook machines with a feed dog drop system. That's whey they FMQ.
As for the darning foot, I don't know of any made for the top clamp feet and that is what the Kenmore 117-959 is. The feet attach with a big nut that clamps them on the shaft.
The person to ask regarding top clamp feet is MacyBaby. She is the biggest collector and researcher of feet and attachments I know of here on the forum.
Joe