I round all of my baby & lap quilts and use binding that I cut across from salvage to salvage. It stretches just fine around the curves as it's a gentle curve. When I do scallops I always use the bias binding. Cut one of your strips the binding width you intend to use, press and pin to the corner, baste and turn over to see if it will work for you. Doing that you won't lose what pieces you have and will be able to tell if it's going to work for you.