Try to encourage the ladies who sign, to include their maiden name, along with their current name.
Dry iron ... and not steam!
Add the laundering instructions to a label on the back of the quilt.
And of course, a label explaining the significance of the quilt and who made it, your location and any other relevant details.
Also, leave a spot on the label for the purchaser's name, so you can personalize on-site right after the auction.
While it may be a hassle, I'd take my iron and know that the heat setting has been done properly.