I really like all the training messages discussed above. I know for a lot of people that first turn to a new collar or harness but sometimes it’s all about breaking the bad behavior. This is just an experience of mine; maybe it will work for you. But before I got my pups I was really fond of this German shepherd, he wasn’t mine but he saw me as family (I was the first/ only person for a while outside the family that he got excited to see come over instead of barking angrily at the door). He had always had a pulling problem, and they had the prong collar too but it didn’t even faze him. The weird thing was I started to take care of him while the owners were out of town, and he never pulled… walked right next to me. He isn’t neutered either. The only thing I can imagine that caused this was the fact that I had my eye forward. I think they looked at him most of the time during the walk, he in turn notices them watching him and assumes (especially shepherds) that he’s leading. Where when I walked him, he’ll look at me and then back to the road keeping pace with me. The key for me was to use my peripheral vision to watch him instead of a direct line of sight. Kind of like telling them, “I don’t care where you want to go”.
But this would just correlate with their natural behaviors and stimuli. For long term retention and social skills building it would for sure be in your best interest to train her. And my solution would just be a temporary fix that would really just work for you; if anyone new would try and walk her old habits would probably break out. Good luck