Make use of everything

A few years ago I took a class one of my friends was giving on paper piecing....well knowing it was something I would not likely use since it involved a machine. I brought this piece home wondering what I would ever do with it. Fast forward a year... daughter and granddaughter spend the night from time to time and sleep in the loft. I go up to find a towel or some other object crammed into the area to cut the morning light. Then comes the big "AHAH!" I have something just the right size to fill that spot! The little quilt (if it could be called that) fits on a spring rod and can be used to cover the window or be moved below to let in the air. Multiple problems solved!

Knot migration

I am wondering how to prevent and remedy knot migration.
This must be a problem that machine quilters never face. It happens when I am quilting and find a knot, that was part of the piecing, suddenly sitting on the surface during quilting.
I've tried back-stitching the first stitch when piecing without great success. The only thing I can think of is taking several back stitches and then cut off the knot. Any ideas? or am I the only one with this problem?