Okay try this. Take the Frixion pen and remark over a line already on the quilt until it has a lot of the ink on top of it. Then try the iron heat. This worked for me. The new ink sinks into the old ink making the old ink new again. Try the ink marks that haven't been exposed to the other chemicals you used to remove them before trying on those areas. I don't know how those cleaning agents will react with the ink. Also have you tried friction to remove the marks? Try the eraser on the end of the pen or a Magic Eraser.