I have a strange way of marking on quilts but it works for me I use press and seal it klings to the fabric and comes right off when I am finished however I machine quilt so be sure to try a sample for your hand quilting
hope this helps

I would try the OxyClean. Pretty quilt, though.

You can also try Orvus. It's a horse soap but is fabulous on quilts. I've been using it for years.....very time consuming.......but well worth it. Leaves quilts sparkly clean.

OMG, my heart is crying for you. I would be so upset.

Use a water soluable pen from the quilt store. I have a blue one that washes out with just a touch of water.

I hope you can get all those markings out. Good luck.