2 year old female Shepherd Mix (Marana)

Valkyrie is a 2 year old female shepherd mix.
She is spayed.
She is good with older kids, not sure about younger ones.
She cannot be with other dogs.
She did fine until the last few months.
Lately she has been attacking my other two dogs.
I am asking a small rehoming fee but will be sending her with a large bag of dog food.
I am trying to keep her out of the shelters due to the likelihood of them putting her down.
She’s a great dog with the exception of other dogs.