I've only had to introduce one kitten to two other cats in my lifetime, so I'm not the best person to be giving advice. However, when my kitten came in contact with my other cats for the first time, they hissed at each other and my other 2 cats were not happy. One of my cats (who's 4 years old now) warmed up to the kitten after a week or two and they started playing together, which they still do all the time. The other cat (who is much older than the other two) got used to him, too, but they don't get along as well as the other one does.
I let them see each other in small doses over a couple of weeks, and eventually they got used to it. So I would just give it some time and see if they adjust to each other. I would get some advice from others though, because like I said, I've only had to do this one time.