3m old female kitten tormenting older female cat..please help!!!?

Your new kitten is going to have lots of energy. She might be trying to become the dominating cat, over the other cat. The best thing you can do is give her lots of attention and try to play with both of them together. That should help relieve some of the anxiety of the older cat. My cat was 18 when I introduced a younger same cat and it took a while, but they finally got along and started playing together. Just give them both lots of well deserved attention and everything should work out just fine.