A stabilizer or an iron on interfacing would be my choice. I have seen a quilt where the handies were folded into a fan shape and appliqued onto a block. Under the fan was appliqued a ribbon bow and streamers. What do your friend's hankies look like? Are they all white with delicate embroidery in the corner? Lace insets in the corners? Are they the same sizes? My mother carried a very fancy hanky when she got married, I carried the same hanky when I got married, my daughter and granddaughter carried the same hanky when they got married. It was the "something old" I think my GD had it stuck in the waistband of her panties! LOL! If your friend has children she might want to keep one special one out for something like weddings and not put them all in the quilt. Just a suggestion.