I have repaired quilts that had holes worse than that. What I do, generally. to fix it, first, is to try and match the fabric. Perhaps you still have some. Make the HST, if that is what it, or they are, and then very finely, with a lot of patience, iron the seams lines in on the repair piece, and applique the piece back on. Do not remove the damaged one, just applique over it. You can get a piece of batting and insert that if that part is badly ripped. The back would have to be patched, using the applique stitch also, but since it is on the back, it will not be so noticeable. I don't know if the quilt is machine quilted. I hand quilt, and have only repaired old, damaged quilts that are hand quilted so no problem, but if it is, perhaps you could take it to the person who machine quilted it and they could do something to help.