My family will be touring in china for 19 days prior to my daughter attending Chinese language schoo

how do we get extension on her visa so she can be a tourist with us and then go to school? My daughter is adopted from PRC as well but a U.S. citizen. From my research I've learned she need her original Chinese passport, her current U.S. passport, copies of adoption papers and a certificate of her naturalization. I have her green card too. with all these documents do I really need a certificate of naturalization too? Cant reach any Chinese embassies by phone or email feeling a bit frustrated. Any ideas appreciated, thanks.