I originally have 3 cats - 2 15-year-olds (both males) and 1 7-year-old female. We just introduced a 3-year-old female (all cats are spayed/neutered) on Wednesday evening (today is Friday morning) and so far it's not going well. The first night we kept them pretty much separated, there was a lot of hissing and growling when they did see each other, the 3 slept in the bedroom and the new one out in the living room. Yesterday, there was still a lot of hissing and growling going on and this morning too. I'm just wondering how long is this going to go on and what can I do to quicken the pace of them adjusting to her? Is it hopeless at this point? Help!