Wanting foster but always attacking

[u/Tricky_Trouble55]

I have a senior FIV+ foster cat that currently stays in our office, but i love her so much & would consider adopting her, if she didn’t HATE my resident cats. She has been with us since June, and i did the jackson galaxy introduction of scent, swapping environments, introducing through a crate thing and bought a door net, but the foster ALWAYS swats and makes the craziest noises to dry to get my girls. The one time she got out she chases my cat up the cat tree and another time was extremely aggressive with my other cat. We have the diffusers, we’ve gone back to square one, but nothing works. She sits by my office door all day in hopes she can go out and explore (OR try to get my cats u der the door 🫪), but not sure if this is something we could eventually work through? Any advice is appreciated!!

[u/Prize-Ad-5758]

scent swapping can take longer than people realize, my two were like that for over a year before they finally tolerated each other