Both such Stunning designs!!A lit Non Fray will do the magic!!!
Lovely butterfly and very cute kitties! When I have cut too close to the edge, I put a small line of fray check to cover that area about 1/8" wide and wait for it to dry before stitching the satin stitches. I've I'm ultra concerned, I also float a small piece of cutaway stabilizer under it. I just pin it in place and cut it away after stitching that part. And...then if it still looks iffy, I'll put a tiny line of fray check on top. If you put too much fray check on, it can discolor the fabric a little.
Pretty butterfly and the balloon cats are cute