how to extend B2 visa in USA B22005-08-23 04:24:19

I would like to extend my parents' B2 visa for another 4 months.
I bought two-way tickets for their returning to china. How to extend my parents B2 visa?
what kind of form do i need to fill in? how much application fees do I need to pay?
What else should I provide to get the extension approved?


Thanks in advance!

B2

I suggest you don't since my