Mineral spirits is the same ingredient in paint thinner. If you pre-washed the fabrics, I bet you can use it on them without running the dyes. Can you create the stain on some scrap to experiment?
Who manufactured the stuff, and do they have a number to call? Timing being what it is, you may not get a response til after Xmas.
If it has a poison warning on, you may be able to track down a safe solvent that way.