Work permit with out family members

I recieved my work permit invitation frim china. But it seems that my employer forgot to include my family members . So it is noted on the work permit invitation that there are no family members. My employer told me that it can't be changed but the company can give me an invitation letter for my wife and baby.
My question is can I apply for my wife and baby at the Chinese embassy for S visa using that letter at the same time I apply for the Z type .