2 days ago we got a 6week old female kitten. She has settled in very well but yesterday we got another female kitten to keep her company. We had thought this new kitten would be roughly the same age but she is actually 12weeks. The little kitten was afraid at first but is know fine with the older kitten, but the older one seems to be afraid of the little one. She growls and hisses and the little one and runs away (though she also does this to a black furry toy mouse which looks very similar to the kitten). I gather this is normal behaviour but does anyone have any advice on how to get them to feel comfortable around each other. They both belong to my 12 year old sister who is understandably worried about the big one hurting the little one so a quicker easier introduction would be beneficial to all. Thanks.