Can we extend my son's visa from Macau? He has South African Passport

My husband, my 2/5 year old son and I have recently moved to Guangzhou and reside there now. We registered a company there. My husband and I have multientry for one year, our son's will expire on 28 Feb. as we, parents, still have valid one and we have enough docs to show that we live and run a business company in Guangzhou!