Try to use a non-woven textile tape or by the yard fusible. The stability of non-woven is needed as opposed to tricot or knits. Cutting the batt in a straight line leaves a straight line of weakness. It is better to cut a shallow curvy line. Try to find 1" wide fusible for straight lines and 2" wide is pretty much a must for curvy cuts. The non-woven tape is much less expensive than the knit tapes.