My sister has a cat that is 14 years old. She got 2 kittens about 6 months ago. Her older cat did not and still does not like nor appreciate these kittens. My sister has accepted that her older cat will probably never get along with these kittens. So, she just makes sure that her older cat has his own place in her house, as he likes to sleep in a cat bed on a side table in the living room. She also feeds the kittens and her older cat in different places in the kitchen. She just has to keep the older cat and the kittens separated and then the older cat is able to 'tolerate' the kittens. That is the only way my sister is able to have three cats in the house. She loves her older cat but also, adores her new kittens.