Z visa for my family

hello , dear sir/ madam . i am i live in china , i want invite my wife and daughter and my son . what i have to provide . my wife and daughter they been in china before , and my son born in china he has visa only for exit from china, as i know it need ,Statement A family but i can not got it becuase my Place of Registration aleppo. ( the / Z / invitation letter i already sent it to syria )

waiting for your answer

best regards

fadel al chaban