in this case the old quilt becomes the batting. The quilting needed is to stabilize the batt is very little but yes you need to secure the pieced seams. Without quilting you would have to much pull on seams.If don's want to quilt thru so much you could quilt it to an inside back layer. Existing Kona white, quilt, extra layer for inside back (to quilt to) new front. Then all you would have to do to put layers together is tack it maybe every 12 to 15 inches.If not tacked or quilted thru all it becomes a duvet which works to.