Several people have mentioned the time involved to Un-sew then add and finish. I used to work in an alterations shop. Many times people have come in needing a zipper replaced in a jacket. When I quoted a minimum of $20.00 they seemed surprised. One thing I was taught in the garment industry was that it takes 10 times longer to repair something than what it did to sew correctly the first time. Besides that, there is always the danger of accidental tearing of the fabric. Unless you delight in absolute self-torture, I would pass this project up. Someone else said "unless they are willing to pay". BTW, I had a few people tell me that they only paid $20.00 for the jacket to begin with. Can you guess what my (polite) response was??