us citizen child living in us with his father wants to visit in the US.

My stepson lives with his father in China. My wife (resident alien) and I (us citizen) want him to come visit us in Hawaii. We are concerned that if he comes and visits, that we may jeopardize going back to China back with his father. All I have seen is that you can get a 1 year multiple entry visitor's visa but what does he need to do to not risk losing his us citizenship and still be able to stay with his father in China?