To answer this question, you have to remember why Suyuan created the club in Kweilin. The Kweilin "chapter" of the club provided relief for Suyuan's friends from the horrors around them, the Sino-Japanese war.
All the mothers in Joy Luck Club have have their own tragic stories that they have carried to America. Suyuan had left her twin daughters behind. An-Mei had seen the horrors of her mother's role as fourth wife. Ying Ying felt the betrayal of an unfaithful husband. Lindo escaped from a loveless arranged marriage. Their backgrounds bond the women together as they live as strangers in a strange land, trying to fulfill the American dream.