Hi. Am a Kenyan Citizen and already have a Chinese X1 Visa my stay in china is 4 years till 2020.

My wife is an Indian citizen with a Re-Entry pass to Kenya. Right now she in India and she does not intend to go back to Kenya until 2020. We have a son one year and 2 months now holding a Kenyan Passport. at the moment they are in Shillong (North-East) and I would like them to come and join me in china.
1. Is it possible they can come stay with me for that long (till 2020)?
2. Is it possible for them to process the application from Kolkata and safe them the long journey to Delhi?

Thanks