Visit from Family members

Hello!

I am working here in China and I would like my family to visit me. I understand that my parents, brothers/sisters and grandparents may apply for either an S1 or S2 visa. I would like to ask if my nephews and nieces can also be considered in this category. They are quite young and cannot be left alone back home and must come with their parents when they visit me here. If not, what are other alternatives so they can also come here.

Thanks!