I would keep the kitten apart from the other cats at first until you see how they react. Have the kitten sleep on a blanket or towel and then put that around the other cats, so they get used to her scent. Since you have four other cats, it might be overwhelming to have them all together at once, so try having her around one or two at a time and see how that goes. Have her spend a little more time with the cats each day, under supervision. If any of the cats aren't behaving well with her, keep them in carriers so they can see each other, but not start a fight. You will have to be the judge of your older cats' personalities and how you feel about trusting them with a young kitten. Some cats are fine with a new kitten; others might take more time. The introduction technique is also a good idea because the kitten will feel safe and the others will have more time to adjust to a new family member.