This is what I would do I would make measure the area that needs to be replaced. Make a block and embroidery on it the year you made the quilt, who the quilt goes to and who made the quilt and then I would hand applique this on to cover the bad area. Then I would give the quilt back to him and see how it wears. I think any thing else will be to much work and it would be better to make him a whole new quilt.