My grandmother used to hand quilt double knit quilts all the time.. I have quilted a few small doublt knit items on my domestic machine... Stretching is a huge issue.. I find if I quilt my double knit with a cotton backing that is preshrunk it works fine.....
I"m in the middle of quilting some double knit that was donated to me to use for my American Veterans Project....
I have done a couple of these for the Veterans.. u should see the older folds flock to the stuff..... they love double knit....