If she's not willing to poo on the potty, you may have to ease her into it. One method some parents use with success is to say DD is allowed a diaper to poop in but she has to ask for it. Try also to get her to poo in the bathroom in her diaper if she's willing. Pooping in the diaper isn't ideal but right now we need to keep those bowels moving. Lots of fruits and veggies and little to no dairy for a few days works like a charm at our house. (as an aside, was she using a potty chair or the toilet? Sometimes splash back can scare a kiddo for a while). Next, work on getting her to sit on the potty with her diaper on. Once she is comfortable doing that, it's time to get rid of the diaper. (make sure her feet are planted firmly on the ground or a very stable stool so she can push). If using disposables, you can start cutting bigger and bigger holes in the back so eventually the poo just falls in the potty, then you can get rid of the diaps altogether. If using cloth, you can loosen them gradually and shift them down away from her bum to get a similar effect. I have heard of moms putting a belt (loop of covered elastic for instance) on the toddler who is having trouble with the final step to mimic the feel of a diaper waistband.
HTH. I gotta run, DD needs breakfast :-)