Colour catching devices in the dryer, overpainting, overdyeing, and soaking in synthrapol to get out excess dye were the suggestions.
I didn’t know about these colour catching devices for the dryer and would have had to run up to the drugstore first. I believe I can’t paint, and did not want to start reconvincing myself about this matter on just this piece. Overdyeing seemed a possible and fun solution (thanks, Margaret!), but because I have synthrapol at home, I opted for this as a first try, overdyeing would still be an option if this one failed. Soaking produced a red flow of water and my heart sank when I was rinsing, but off into the washer, hang up to dry after taking it out. The basement is dark and the lights don’t really make it possible to see anything, but the photo with flashlight was promising.
I left for a visit with a friend for three after hanging and tried not to think about it too much while I was away. Upon our return I had to take care of our failing heating system first and get somebody to fix it (on a Sunday) before I could look after the quilt. But then relief: every stain was gone, this quilt would not be transformed into bookcovers, another possible solution I had thought of. And it won't be a UFO.
Monday I spent finishing the quilting of the background.
Now I have to decide how to the lines.