There really aren't any quilt police (although some people think they are honorary members!) so it's your quilt, your decision. Put in one layer or several layers. Back it with muslin, flannel, fleece, quilt fabric, or anything you want. Tie it, hand stitch it, or machine stitch it in any pattern you want. Remember, this is YOUR quilt and YOU design it to be what you want. No rules, only the satisfaction of doing it your way for yourself and/or your family and friends.