Give it time! As fluffy said, they are trying to establish the hierachy. We've used Feliway in the past, and it really worked a treat with calming our boy down after we moved and on fireworks night. My advice with the Feliway, make sure its in the main room they use, it doesn't work as well if you put in a hallway (in my expreience anyway!)
Help! In the summer one of my neighbours threw out her three year old cat. The cow had never allowed it out before then because it was covered n fleas evicted her. She took refuge behind my shed and it was about three weeks before I realised she was just dumped and not going in at night as I had thought . Anyhow neighbour agreed to let me take her on (actually she offered her to me) so she has been with me ever since.
But my other cat hates her....sort of. They will share a bed (not touching) they will touch noses too however, this ends with my Tortie (who has a right snotty attitude) clouting the little one (stunted growth due to kittens at 6 months).
There is some play in there too but the little cat has scratches near and above her eyes which I think has come from the Tortie.
Is Feliway worth the cash?
Going to have to see a vet this week now with the little one as she just looks a bit rough around the edges although she eats like a horse and has put on weight since I got her. She no longer has bald spots etc and her coat seems in good condition.
Any advice to settle them down? I do stop the Tortie if she is being aggressive.