parents visa at shanghai

Anybody's parents got visa at shanghai recently. My parents want to come later this year. I heard the situation for parent visa was not good at shanghai. My mum came to US three time, stayed just 2-3 month for the first two times, but last time was 1 year for taking care of my daughter. That was 2002.4 -2003.3 My father should be ok, he came here at least 10 times, for family reuion or business, and never over 2 month. So any people has any advise on their situation, they should go get visa together or seperate, or my mum is not even worth to try. BTW, I have a brother at shanghai, me is b1-f1-h4, went back to China last year for three month.

Thanks a lot, and waiting for your response online