You can go to the Exit & Enter Department under Jilin Public Security Bureau to apply for extension of visa for them. In fact, they will be issued a new one with 0 entry with 30 days or more stay duration, please take the following documents:
Their original passport
copy of their chinese visa on their passport
each one fill one application form attached with one passport photo
copy of your passport, Chinese X and residence permit
relationship certificate, marriage license, birth certificate

Dear Rizwan,
I hope you will be fine. I am comming Changchun institute of applied chemistry for one year PhD research program in september, 2013. Are you still there. I want to contact you. Can you please send me your email/cell number via email.
Regards

Zaheer Ahmad
E.Mail: gmail.com|saubanzaheer