I'm certainly not a pro with quilting, but couldn't you iron some muslin or similar material to freezer paper and have your quilting helpers sign it...then you could size the label (before or after signing). I plan to try this with a quilt I am making for a wedding, and have guests sign block that have been adhered to freezer paper. I even through of using a rubber stamp for decoration. Let me know what you think.
Sibble