Herbal Supplements/Essential oil for bullying?

Hello,

My younger cat Nika, has some issues with both being territorial, and jealous, which results with her attacking my older cat. It doesn't happen that often, so I'm that worried, but I'd like to decrease her attacking to even less. We do a lot of playing with different toys, we do mental sitmulation(stuffing treats in things, having her search for treats), and training. 

I have heard that some people have had success with herbal supplements, and essential oils. For those of you who use them, or have had success with them I have some questions:

What have you used?

How did it help?  

How long did it take to see positive effects? 

What did you use it(spray, diffuser, trein water, etc.)

THANKS A TON!

Please be very, very careful using any essential oils on or around your cat. Many are toxic, even fatal, since cat systems are so sensitive.

Have you tried feliway? The diffuser or spray could help.