You can add sacarfice(sp) borders to the top. I do this when I have cust quilts that are too small and they want a certin design in them.
I cut a 4" strip of muslin,baste stitch it under the scallops so the scallops are on top. do this on all 4 sides.
I never float my tops,so pin it the bottom to the leader. Baste the top to the batting and back as usual.
Baste the sides down as you go. Then you can do 2 things...quilt the scallops with the borders on and they can be trimmed off when top is done. OR when you come to each scallop,you gently remove the border as you quilt and then baster only the edge of the scallop before you quilt it. This takes time but will work. I do hope you are charging her custom prices for the quilt