Need help with cat behavior
For context, my husband and I moved into an apartment complex when we got married that had a large population of abandoned cats and the babies of those who were abandoned. Like to the point residents were trying to help and we would get written warnings to stop trying to feed them or TNVR them. Believe me, we tried to make the case for it and the property management started shooting them.
I had never had cats before and my husband and I left the door open to discover our first sweet baby on our couch. He is a bit territorial, but takes praise and discouragement well. He even grooms my black lab. Then we got our second. I walked outside to stop a cat fight and a kitten jumped into my arms. I didn't have the heart to put her back outside. Our first was weary at first, but took a liking to her within a couple days. They get along great.
The third is a whole different story. She is stark white and pink. She has alien eyes, is polydactyl, cant retract her claws, and drools when she gets attention. We saw her get dumped and eventually brought her in (she was quarantined until we went to the vet). The issue is that she wants badly to be friends with our first and he is not a fan. The second cat she does not have any interest for and will yowl if they are within 10 feet of eachother. She also swipes at my dog. She absolutely loves humans though. Granted, I dont have much cat experience, but my husband does and we can literally summon her with a song, it seems like she never knows what her next move is, copies the other cats, and just constantly does such weird things. We lovingly call her "pawtistic".
Our other cats were at least somewhat predictable and able to learn behavior. She is just throwing us for a loop. We've tried treats, extra play, desensitization, extra love, discouragement, slow introduction. It just seems like she always snaps back to her old ways of yowling, swiping, and chasing. We love her and want her here, so I'm trying to figure out if maybe she needs a vet or behavioral visit or a different setup or something. If you have any experience with this, please help.