Rit (like the fabric dye you can buy in the grocery store) makes a product to remove color that has bled onto other colors. You can find it next to the bottles of dye. I used it once years ago to remove red that had bled onto the white stripes of a cotton top. It worked well for that. I can't say how it might work on a quilt, but if all else fails, that might be an option to look into.