If the marks don't come out, no matter what you try, you have a few options ...
1. go ahead and quilt it as marked. for every one person that doesn't like a quilt, another 50 will line up who do. give it away or hang it up and let everybody else convince you that it actually does look better than you think it does. :wink:
2. get some paint pens and turn the "mistake" into artistic embellishments. then refer to #1 above
I guess you could use it to decorate a landfill (many of my mistakes are doing that. LOL) but I'll bet picking #1 or #2 would feel better. :mrgreen: