l have recently added a 12 week old female bengal to my home. I already have a 9year old moggy and a 7 month old female bengal. The moggy has accepted the kitty, from day one. The bengal is another story. She has become really aggressive toward the kitten, and even toward the moggy for being friends with the kitten. She hisses and constantly growls, whilst hiding under the table.

She is even angry toward me and my partner!

what can l do???

same here.
i have two 7 month old cats, both male. got a new 9 month old bengal.

When i got the kitten home i first of all washed it, the cat comes from a breeder so it has smell of many adult cats on him.
i rubbed him with a towel my other cats sleep on.

One of my cats was really scared of the kitten and the other one was agressive. Both hissed at him and my bigger cat even almost roared he makes very deep grrr from belly.
the kitten first tried to approach them but got scared.
he will sleep in my bedroom for the next days... he get different food anyway and has his own toilet.

The second day my kitten learned the sounds from my cats and started hissing and make the Grrr sounds with his belly....
i let them 3 sit with me on my bed and play with them so they slowly can relax in eachother presence.

i guess this will take a while.