If she won't take F/T, you may have to feed live, or at the very least pre-killed even if you don't want to. Feeding live once won't keep them from switching to f/t if they are willing to do it. If feeding F/T obviously make sure it's fully thawed and up to temp. You could blast the head with a blow dryer right before offering as well...then it's time for the zombie rat dance! If that doesn't work, you could try braining it and leaving it in over night.

As to the live feeding issues...maybe she just hasn't had rats before. Try a bit larger mouse...like a hopper or small adult. If you're dead set on rat pups, get some soiled mouse bedding and rub the rat pup in it right before you offer. I've used that method to trick my ball python who only eats mice before.

However, if she refuses to eat f/t, as many of mine do, I keep a cage to take care of any refused feeders. I don't have the problem of having rat pups refused because I have boas. But, if there was a refusal, I would take it back to the petstore.