I would write up a couple lines and stating that it's not going to wear like the rest of the quilt, and may not launder well. Make 2 copies. Then meet with your client and have them sign indicating that they understand. Keep a copy & give one to the client. It might have lots of sentimental value and they may want to keep it in. If they do want to proceed, you will probably have to use an iron on stabilizer. Make sure that you get one that will adhere at a low iron setting as acrylic will melt.