can someone appear for another person

Here are the China Business visa application procedures:
1.You (or someone on behalf) may come to the Embassy with complete visa application documents required, for appointment of interview. The requirements include: visa application form; "Invitation Letter of Duly Authorized Unit" or "Confirmation Letter of Invitation"; One formal introduction letter from your company telling your identity, the purpose of visit to China, and supposed duration of stay in China; photocopy and original of your ID card and certificate of incorporation; hotel reservation and round-trip air tickets; your recent bank statement; your passport and photocopy of its data page; a complete list of the documents you submit; other deemed necessary documents by the embassy.
2.You should go by yourself to the embassy for the interview.
3.go to collect the visa with the ‘’Pick-up Form’’ if it is issued.

You may also look up this info at the bottom of this page: https://www.travelchinaguide.com/embassy/nigeria.htm