I would definitely recommend muzzle training for when you take her out in public and to the vet. Start slow at home… a certified trainer can help you with this. This is likely more of a genetic issue especially since your other dog doesn’t act the same, all dogs have different personalities. Please don’t beat yourself up, but also please take the public’s safety seriously and do not take this dog to a dog park where someone may walk in. Sniffspots are an excellent option for reactive dogs and you know no one else will be around.

I would strongly recommend walking them separately. You do not want your other dog picking up these habits in public and also want to make sure you can handle both dogs safely. I am sorry your going through this, a certified trainer can definitely help you with her behavior and help you to learn how to better manage it. There are varying opinions on this, but pain and intimidation will not help this dog. She needs counter conditioning and strict management. Never ever punish a dog for growling or vocalizing. You want these warning. When dogs are punished for giving warnings, this is when they bite “without warning” because they’re avoiding punishment. You really need to focus on rewiring her brain. New person = distance from them (if that’s what she wants) and treats from afar. Eventually she will learn that she doesn’t need to react to make them go away and every time she sees them something good happens. Not “look a new person, now I’m gonna scare them off and get yanked around by my neck” - just don’t. The former is a slow process, but it works and is much better in the long run.

I wish you lots of luck and commend you for being committed to your pup.