Forgot to say the reason for the new cat. He was attacked by an Alsation so he's being kept inside & getting lots of TLC. The other 3 are annoyed and I'm trying to give them just as much attention but they are punishing me by spending most of their time outside. HELP!!!
I appreciate you want to give the new cat lots of TLC as he has been traumatised, but could you keep him in a spare room for a while - at least then your other cats will come back in the house, although still realising he is there. They will be jealous at the moment, but with time, they should get used to him.
We've had this situation. Initially we tried doing what jules suggested - keeping new cat in separate room and also did things like stroke new cat while wearing sock on hand and then stroking orginal cats and then back to stroking new cat to muddle up the scents. When we eventually introduced them all after 2 weeks (longest two weeks ever!) one existing cat made friends immediately, the others spat and hissed. We had about 4 weeks of tiffs and then most settled down. However, after 2 years our neutered female has only just accepted the new one - she still whacks him if no-ones looking. Be patient and let them get on with it.