I've seen this done and it looks great. I don't see how you could add to it without taking the binding off, but you would just sew the ruffle "bed skirt" onto the wrong side of the finished quilt.
Originally Posted by sahm4605
i would put a "ruffle" on three sides of the quilt maybe. it might look cute. otherwise I would take off the binding and add the extra fabric in all three layers. in maybe a round about quilt as you go fashion maybe?