Three months ago I rescued three kittens. One 3 month *boy); two 1 month (girls). I already had one resident cat (girl) who is about 5 years old (also rescued). As of 3-4 months later, the resident cat will not accept the new cats. I had them vetted right away and did shots, spays, etc. They are to live in the barn. I immediately put the 3 new ones in the tackroom. The resident was a little off for about a week, and then came back to her normal self. She is a lovely cat. Very friendly and will follow you anywhere. However, she will not accept the new ones after all this time. I still have them separated. The could smell each other through the door and I part up a screen so they could see each. After about 2 months, I let “littles“ out of the tackroom. The resident immediately attached one of them, and I mean attacked. I separated them. Another few days I tried it again, the resident attached, and not just a little. Lots of growing; the little went on her back and didn’t move. The other two littles stay far away, watched and then hid. I have tried this multiple times over this time period. The littles are scared to death of her. During the day the resident is out of the barn (sometimes I take her out). I open the tackroom and they get the entire barn. They are very bonded and can hardly wait until I come and spend time with them. They come running to me. About a week ago, I opened the barn door and let the three out for the first time. The resident immediately took after them growing, etc.; she was on a mission. The littles ran back to me and then the barn. These cats are outdoor cats (I rescued them from a barn). I am not at the point where I think I have to rehome either the resident of the new cats. One of the littles is going to really get hurt. I do not want any to leave. I just do not know what to do any longer. I have tried all the introducing steps many times and am still having no luck. Maybe somewhere out there can give me some insight. Thank you all.