I would add dark pink borders in QAYG fashion. I would cut 8-1/2 inch strips of pink, 8-1/2 inch of batt and 8-1/2 of background fabric. I would lay the fabric for the top and back on either side of the old edge with the batt on one side, pin, sew the seam, and flip the fabric and batt out and then do the other sides. Once all the sides are done and flipped outward, I would then quilt and bind.