Hey suzanne,
First off I would just offer the f/t after a 2 week period, this will allow them to settle in and de-stress some as well as getting them a little hungry. If your feeding methods allow, leave them over night and hopefully "supper" will be nothing but a belly lump.
If that does not work on the second attempt, (3rd week from now) try to tease feed them. Using long forceps and a warm meal item slowly tap the snake about 2/3 way down its body, not on its head as this may make them shy away from the food. Once the snake grabs the item hold VERY still until it either pulls it from you or it starts to swallow the prey, then move very slowly to let go and allow them to swallow.
That will give you a few weeks of trial, hopefully they will start on f/t without a problem, however, I do have a male ball python that flatly refuses anything dead, just be prepared.
I hope this helps.