Thanks. :-)
We don't have a Joanns here. I will see if I can get some dye grabber from somewhere next week. Will ask at my LQS if we get it here.
I've put the big piece of fabric in a bucket with the Jet Stop stuff, it says on the bottle that it prevents runs and sets dyes. It looks like the water is still going blue though, so not sure if it would be enough for the Baltimore block.
I'm kind of over the panic now... if I have to remake it, it's no big deal. So will be a bit of an experiement to see if I can set the dye! :-)