Notarized certification of kinship

I am trying to apply for residence permit for my son who was born in Thailand. He entered Shanghai on an S2 visa. I went to the Shanghai Entry-Exit Bureau and the immigration officer told me I need to get my son's birth certificate notarized at the Chinese Consulate in Thailand, but we are already in Shanghai. I read somewhere that it is acceptable to get the birth certificate notarized in the Thai Consulate in Shanghai but I'm not sure if this is acceptable. Please advise.