You also need to provide the following documents besides the invitation letter,
A valid original passport with at least two blank visa pages and at least 6-month validity.

One recently taken passport-sized photograph affixed to the visa form which shows entire face, without a hat.

One completed Chinese Visa Application Form signed by THE applicant.

Your family member can't gat a China business visa, they can apply for tourist visa to China. They don't need to provide the invitation letter from a China company, however, besides the above the 3 requirements, they also need to provide the a copy of E-ticket or travel itinerary.