E.M.
my son was like this (but not my daughter - they are all different!)
After he was trained, he would ask for a pull up when he needed to poop.
We did this for about 6 months, then I told him that when we finished this box of pull ups, it was time for him to go on the potty. He counted the pull ups every day, and we would talk about how there were only 10 more days of pooping in pull ups, then 9, etc. On the actual day, I put his potty where his poop spot was, by the kitchen. That was a hard day for him - he wanted to go in his undies, but I wouldn't let him. We had gone to the dollar store and picked out 2 special gifts for him for after his first and second poop on the potty, and did lots of talking about going on the potty, playing it up. He really had to go badly, and when he just couln'dt hold it in anymore, he finally went on the potty. I went with him and held his little hands (his request). We made such a big deal out of it! I aslo took him to Dairy Queen and bought him a big ice cream cone as a special reward since it was such a big deal for him.
If you think that might work with her,give it a try. For now, I might even back off and let her go in the pull up just to give her a break. As some other people have mentioned, lots of fiber to make it easier for her to go.
Prunes, pears, etc.
Imho, not worth all the tears and trauma. See if you can find a way to remove some of the drama around it, and let her own the process. We also read lots of books, watched some videos, and my son really liked the book "everyone poops".
Good luck - it's so hard when they won't do what you want them to do!