Hey! I need some help! So we got a Maine coon about 3 weeks ago. His name is Kovu, and from the moment we got him he has been the perfect kitten. He is about 11 weeks old. He loves and snuggles and kisses. Me and my boyfriend live in a 2 bedroom apartment and we work 40+ hours a week. So we figured Kovu gets lonely during the day while we are at work. My boyfriend's family had a friend that needed to get rid of a kitten who is around 9-10 weeks old. So we decided this would be perfect for Kovu to have a sister, Kiara. So we brought her home today. At first she was scared of course, but we were able to hold her and pet her. As time passed and she interacted with Kovu more, she became hostile. She hisses and growls constantly. We have separated the two kittens for hours at a time and some parts of the day we have allowed them to be in the same room. Kiara has only become worse. She has began attacking us and hisses constantly at Kovu even though he is not around her, just in the same room. Kovu is dying to play with her and acts sad that he can't go near her without her becoming angry. I know we need to give them time to adjust, but what is some advice to make this transition easier for them?