Who is Pei-o from Wild Swans: Three Daughters of China and what is their importance?

Pei-o is the original name of the man who married Lin, becoming Yu-fang's brother-in-law. He was a warder in a prison. He later changed his name to Xiao-shek, which means "loyalty to Chiang Kai-shek". He, Lin, and their children die in a famine.