I have repaired an old quilt using the exact method you described and it worked just fine, catch a bit of the batting in your stitches. Amazing work for a first quilt. Also want to say, I am in the process of making that same butterfly from old hankies. The hankies will always wear more easily than the surrounding fabrics since they are so thin to begin with--maybe daughter needs to display only this quilt and have another one made for her to use.
