S2 Visa for my mother

Hi,

I am scheduled to travel to Shanghai in August 2014 with a Work Permit. My infant daughter will accompany me on a dependent one. I would also take my mother with me. Is it possible for me to get a S2 for my mother? She will stay with me and my daughter, and all her expenses will me borne by me and she will be under my responsibility.

As I understand, S2 has a 6 month validity. Can I request for an extension of the validity from Shanghai itself?

Please help me with responses for my queries.