Peckish

Exactly what I was going to say. I was horrified to see that someone had recommended this as a treatment. I'm rather late to this thread and was praying this advice had gone unheeded!

The marks from a water soluble pencil will dissolve in water. You can find them in quilt shops. They are designed specifically for this application - marking quilting lines and then disappearing. As with all new products, test on scraps before proceeding, and make sure you retain the package's instructions for how to remove that particular product. I've known many a quilter who assumed that since one product disappears with an iron, they use it for another product, which unfortunately sets permanently with heat.

Jane Quilter, I'm very happy and relieved that you found something that will remove the markings! Make sure you post a photo of your quilt when you're done, we'd all love to see it.