Paint them with COP/c paint pens, they are perm dyes for fabrics and they are blendable... they are wonderfull.
They hot ribbon art ladt selles them or you can order on the internet.... theyare the best painting on fabric pens I have ever seen and they are refillable... you can buy in different sets and refill the ones you use the most.... and even after they dry you can come back with the blender and they reactivate....Lennie is her name and she is called The Dutch Quilter... she is a most wonderful person. Connie