How old are your snakes? Older snakes can not eat for months and no harm come to them. It is distressing for the owner, but some balls are very picky eaters.

Also, if you just got them a few weeks back, she may still be getting adjusted to her new enclosure or the feeding item. Did her previous owner feed her f/t? If not, you may want to stick to what he had been feeding her until she adjusts then try switching to f/t. Did the previous owner report any feeding issues?

Good luck and let us know when she eats.