I posted about our rescue kitty here: www.mumsnet.com/Talk/the_litter_tray/2048397-Rehoming-cat-to-a-farm
He has now been with us since Monday night (was snipped and inoculated on Tuesday) and we are introducing him to our 3 other cats. Our old boy is not fussed and there is very little aggro. Our 2 older girl cats are a different story - they're scared of him and there is lots of hissing and growling. We are rotating rescue kitty through the 4 rooms in the house that have doors so that his smell can get everywhere, and we're letting him spend some time with the other cats under close supervision. Is there anything else we can do? We don't want to stress our cats unnecessarily, it's not fair on them. How long should we give it to see if they will get along with each other?