when i brought in mama kitty with her babies i put up a baby gate to try to keep them separated from my other kitty bella. it didnt work lol mama kitty just jumped over the fence which was fine because bella was the one instigating thing but then within 24 hours bella learned how to climb over the fence lol
One of the things Anita and I do to introduce a new kitty into the house is keep her (we've only had girls) in a spare room with the door closed for a few days.
Kitties smell each other under the door.
Then we open the door, but monitor contact.
With Miss Teia (do a search in this forum and read her story in full), we used a baby gate in the doorway, as all our current kitties are jump challenged.
how long have you had the new cats? did you slowly introduce the new cats to your kitten or did you just bring them in expecting them to get along? what you need to do is try to keep them separated and slowly introduce the kitten to the new cats. eventually they will start to get along but right now they dont know eachother. i would do it one cat at a time.