You could type your letter on the computer and then print it on Printed Treasures. Printed Treasures is a fabric that has paper on the back so you can run it thru your printer. Then you peel off the paper and stitch it on the back of each quilt. That way, the letter stays with the quilt with no chance of it getting lost. I did that with a quilt my MIL started and I finished for her after she died. It's a nice keepsake.