Pit bull terriers are dog aggressiveby nature. Pit bulls from fighting lines are even worse. Pit Bull Terriers from fighting lines are designed in every aspect to be killing/fighting machines which means they have added dog aggression, aggression more so then even the average Pit Bull Terrier and because of this, few of these "fighting line" animals are bred, and fighting breeders who breed them is almost impossible unless you have inside scope. Dog fighting is illegal everywhere so those who breed these "super-hyped, hyper-aggressive Pit Bull Terriers, only sell the to those who intend on using them either for hunting hogs, wild game or for fighting. How you got one of these "fighting line dogs" is beyond me, and even if the dog was of average mutt, Pit Bull pedigree it would still be dog aggressive.
If you knew this dog was from possible fighting lines you should have gotten rid of the dog before it even set foot in your house to cause harm to your other animals. This dog will KILL your other animals if you do not have it re-homed. No amount of separation, training and hoping will re-wire this dogs genetics and genes. This dog was bred for dog on dog aggression and just like every other Pit Bull it has no qualms, if not properly socialized or trained about seriously mutilating or killing other dogs.
Get rid of it. PERIOD.
Pit Bull Terriers are dogs who are bred for dog/animal aggression. Without the dog aggression trait they wouldn't make good fighting dogs now would they? Fighting dogs are surprisingly human friend, since these dogs have to be handled by humans in the ring and dogs who showed aggression towards human handlers in the ring were killed/culled. Pit Bull Terriers can be incredibly loving towards humans, but they are naturally very aggressive towards other dogs.
I've owned tons of Pit Bull Terriers, and Pit Bull Terriers from Jeep, Red-Boy and Colby lines are those with notorious aggression since these dogs are bred with the same "game" traits in mind that past "fighting dogs" were bred with.
Pit Bulls by nature are very dominant, independent, head strong, prey driven and determined breed, so it's no surprise at all that your dog disregards you or doesn't listen. This breed is also very high energy and high sprung.
Pit Bull Terriers are NEVER recommended for multiple dog homes and although some Pit Bull Terriers are raised with dogs and get along with them fine, many are dog aggressive and many that aren't dog aggressive right away, can display or revert back to their innate traits and behavior if the situation arises or because of unknown circumstances. Due to the breeds ability to inflict SERIOUS damage on both dogs and people it is NOT recommended for first time handlers are those who are inexperienced handling this breed or other large powerful breeds. This breed of dog can easily overwhelm an uneducated person. You bit off more then you can chew. Please have this animal re-homed before it makes "Headline" news for attacking some old bats Poodle.