New young tame 'feral' kitty added to house has upset things. Help

Help..We brought a new young tame feral kitty in the house. I was against it at first because I knew this temporary rescue was going to become permanent. Well, I was right. Wife, and I guess me, is attached. We had two grown cats already that got along fine. The little one, inadvertently has put everything in turmoil. The second cat we adopted now is a total "B". She's a a long hair black cat and is jumping on gypsy, the kitty. I'm scared she is going to hurt her. We are putting the pheromone drops in her food but they are not working anymore. How about diffuser?

Welcome to TCS, geauxtigers

A diffuser could work, but really the introduction process is the big thing. Did you go through any of that?

Here's an article on it.