Charis joined our family on August of 2011. At first I was worried about Bimbim because she was always the one who had a hard time adjusting to changes, but when Charis came through the door both cats checked her out and everything was surprisingly peaceful. They had their nose to nose greetings then just left each other alone. I had a bit of a close call, though, when I tried to feed Charis, Bimbim went straight to the dish and tried to eat Charis' food, but thankfully Charis did not do anything.
After a while Charis became more comfortable and started exploring our home. Sumo kept watching her and would swat her even without provocation. Charis, on the other hand, thought it was a game and kept trying to play with Sumo which irritated him even more. I thought about keeping them apart but I realized that for them to live together they had to learn how to handle each other. So I just monitored them and the only time I stepped in was when one was being abusive. Otherwise I just made sure that the cats' nails were trimmed and that Charis did not get too excited around them.
Now, four months later, the cats and dogs live in harmony. The only time the cats get upset is when the dogs are so excited they invite the cats to play. Do the cats still swat the dogs? Do the cats still threaten the dogs with hisses and growls? Yes to both - when they deserve it. Do I worry that one will harm the other? Not at all. They may not be best of friends, but they are now family.