I cant believe I missed this!
Sorry you had to rehome Sassy, but honestly? that was about the only thing you can do. what's that saying....
Dogs fight for the right to mate, Bitches fight for the right to live?
Something like that anyway. it's extremely hard, and often impossible, to stop females from fighting, once it starts. Spaying does not help, once it starts. it will only help before it starts.
Instead of getting your boys neutered, you should just get your girl spayed. She is at a high risk of Pyo the longer she goes without spaying. I say that, even though I have an intact female. I am terrified I'm going to lose her because of a metal allergy (she nearly lost her foot after having an abscess lanced with a Stainless knife) But I'm so concerned about Pyo that I'll probably pay for my vet to get all new tools (there are different metals used in surgical tools) and use the laser, put her on hefty antibiotics, anti-inflammitories and anti-histamines, and take her home right after to keep her away from their stainless kennels and bowls and such... it's going to cost me $700 to spay my 8lb dog, but i'm becoming more afraid of pyo than her metal reactions...