[smplocher]

Idea: I've made lots of quilted purses and quilts. Do a quick meander (wandering around with no clear pattern - can be large-ish) stitch around the outside fabric and the batting. That might help. Someone else suggested tying. You could also tack all three layers together without too much trouble I would think. Set your machine (if you can) to a really close zig zag and let your needle go up and down a few stitches a few inches apart. That would help with the shifting problem.