try hairspray it might help it works on some inks

yes i have also heard hairspray and my granny used fingernail polish remover

I have a spray bottle with distilled water, a teaspoon of alcohol and a few drops of clear dish soap. The soap acts as a wetting agent penetrating the ink. The alcohol wipes out evidence of tell tale blue or purple. I keep the solution in the refrigerator to prevent mold from growing in the bottle. This works with the fabric markers. Otherwise use hair spray.

Seems like you've got a few good solutions to your problem there dgrammy. But if all else fails you might try
'abra cadabra' magicians use it to make things disappear!! Sorry for the levity there I just couldn't help myself hee hee.

If it is the blue marker, it is supposed to come off with a solution of water and baking soda. I was told to stay away from the purple marker. That is what we were told at an heirloom sewing class. If it is permanent... I don't know. But... I hope something works.

I had the same problem, my water soluble marker wasn't water soluble so I just sprayed it with pre-wash stain remover and hoped for the best. DIDN'T WORK!
Please don't use polish remover or if you do be very careful on what fabric you use it. It dissolves some fabrics, they just shrivel up like being burnt, I even stripped the lacquer of my coffee table while using it to try and remove spilt nail polish. Come to think of it I still haven't fixed that boo boo.
There is a acne gel that dollmakers use to remove stubborn stains, it contains 10% Benzoyl Peroxide and you apply it straight and leave on overnight, but IT is peroxide so you have to take care with it. It removes biro, texta and all sorts of stains from leather, vinyl, etc.
hugs n roses, Meganne

I thought hair spray would work also. This is a recipe I use and it works almost all the time on everything. Equal parts ammonia, blue dawn (has to be the blue one), and water. Cross your fingers.
:o)

well, by the time you have tried all of these remedies, surely something will take it out. If it won't budge, add to the design and cover it up, cause you have way too much time involved now to quit!

I remember that happened to me once and I still didn't get it out...Me and the pen fell out of LOVE and it has not been seen since...LOL ;) *2U

We were warned NEVER to apply heat to a diappearing marker in an heirloom class. Also, I have had the marks return later. I never apply heat to any marker until it has been removed. This doesn't help you, but maybe in the future. Chalk is a good marker or soap sliver. Also, colored pencil markers (made for marking) seeam to work well. They come in several colors including white, pink, blue, yellow. They will rub off so you have to be careful to use right away.Hope the other hints work for you.

If all else fails maybe you could add another smaller design to cover the marks , ONE THAT WOULD ACCENT THE LARGER DESIGN. Hope you can fix A flower for you