I enlarged the quilt on our bed by making a strip about 14 inches wide by the length of the quilt for each side, sandwiching it and quilting it to match, binding the ends and one long side........then I stitched each piece by stitching in the ditch of the binding on the 'original' quilt. It looks GREAT and you would think it was meant to be that way and not an add on.
I hope this makes sense to you.