Sounds like she may just be very food aggressive.
We had a German Shepherd for nearly 15 years and he was extremely food aggressive like so. It's hard to break a dog from this habit, so we always fed him separately from our other dog.
Your dog most likely became food aggressive because she was starving during the time of being a stray. Most of the time food aggressive dogs never get adopted out because of the danger it could cause.
The best I could say is always feed her separately from your other dogs. Make sure the other dogs aren't near her when you're taking her to go eat outside. I assume the excitement of wanting to eat made her bite because she thought the other dog would steal her food.
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