I've used rubbing alcohol to get rid of accidental ink stains. Success may also depend on how long the marks have been there. I have a quilt that was marked with pencil for quilting--left too long that nothing seems to be going to remove those marks. The suggestion of covering the marks with embroidery may be your only solution.

I would wash after quilting. I have yet to have a stain that the following would not take out: A paste using blue Dawn, Baking Soda and Peroxide. Spray spot(s) with a little water; place blue Dawn on spots, sprinkle with Baking Soda and then spray with peroxide. Rub in with a toothbrush. Leave set for at least an hour or even longer. Repeat after each wash as needed, maybe allowing more set time.

Shout worked for me.

Acetone will likely work. It’s used in labs to clean up all sorts of chemical stuff

finger polish remover is made of acetone and works well for most anything. Also I have some Grandma's secret spot remover which I got at Hobby Lobby which says it will take out ink stains.

Did you try the iron in a small out of the way spot? The disappearing ink with heat pen could be what you have there too.

I successfully removed my young granddaughter's "art" work with a ball point pen from my easy chair with baby wipes, no trace left! She managed to cover a large area in just the few minutes we had our backs turned.

Years ago my husband scratched his back with his ball point pen, he didn't realize it was open. Hair spray got that ink out.

If I remember correctly, many years ago, I would remove ink pen leaks from my white lab coat by soaking the area in milk overnight, then washing. Sounds crazy huh?

I think Carbona makes an ink stain remover. You can usually find it in Walmart or grocery stores in the laundry section.

I use Motsenbockers Liftoff Stain remover products, there are 3 formulations that remove almost everything you can think of including ink. I bought the trial set which has 2 oz bottles of each of the 3, a little goes a long way. Like with any product you want to test in a small area.