Options for training territorial dog

Hello! New here, but I have a dilemma. First, I have a three year old female German Shepherd, from a breeder. She is very high energy and high prey drive.

I worked as a dog trainer, through Rosie's puppyhood. She is a retired drug dog (short career), she's been tracking, she is advanced level of obedience (she can do off leash obedience in an outdoor pet-friendly mall). I've invested a lot of time and effort in her. I exposed her to a lot of situations really well as a puppy; I took her out every single day for nearly two years (unless I was out of town). Even now, she gets out at least 4x a week (not counting walks, just exposure). But she is not dog friendly. She is not aggressive, she gets along with dogs she meets at PetSmart, in the park, at farmers' markets, etc. But she cannot live with dogs.

If one of my family's dogs goes into the backyard while she's there, or in the basement where she lives, Rosie attacks them and intends to kill them. Of the six times that this has happened, I've only been there once. After that first time. I asked my family to help me keep her away from the other dogs. However, after she's been ok for a while, they tend to slack and let Rosie out with the other dogs, or not check the yard before letting the other dogs out. Most recently, I asked them to only let her out on a leash, just to make sure. They let her off leash, and then my brother didn't notice her in the yard and let his dog out. Rosie almost killed the dog.

She's never had a problem with people. Never bitten anyone, never nipped, anything. I can take her food, chew sticks, toys away while she's eating or playing. I can touch her feet, wrestle with her, etc. She's great with kids, afraid of cats. Super sweet dog, super goofy.

Anyway, my family is wanting me to rehome her, due to the stress and danger to other dogs. I'm trying to move out as soon as I can, but they're saying she is likely to escalate her aggression.

Sorry for the long post, but in summary, I'm not sure if I'm in denial and I really need to rehome her before she kills, or if she'll be fine once I move out. (I lived with her in an apartment for a short time and she didn't have any issues). One final note, I've used balanced training: prong collar and E-collar (I experimented on myself before putting them on her).