How to stop sleepy feet??

[Steppingfeet]

The issue now seems to be less about the knees and ankles, and more about the back and neck.  In terms of alignment.

But in deference to Tradition, I'll call it the z&z combination (zafu and zabuton) rather than a mat and cushion

G, my understanding is that the trick is to raise the butt above the knees. The portion of the legs below the knees, then, just tuck underneath, and help to provide stability. But it is the upward angle from knees (making contact with the zabuton) to butt (sitting atop the zafu) that really aid in sitting upright on the floor with a well-positioned spine.

There may just be some grumbling in the spine from lack of good posture, but if issues persist, try lifting the zafu cushion a bit higher by placing something underneath it.  My zafu has become somewhat deflated over the years so I keep a folded towel underneath for added lift.

I couldn't figure out how to meditate sitting upright on the floor until I discovered these at the Omega Institute in NY about ten years ago. They have meditation halls with those cushions, meditation benches, and meditation floor chairs that have back support.

Good luck!