In 1921, the Negro Southern League joined Foster's National Association of Colored Professional Base Ball Clubs. As a dues-paying member of the association, it received the same protection from raiding parties as any team in the Negro National League.
Foster then admitted John Connors' Atlantic City Bacharach Giants as an associate member to move further into Nat Strong's territory. Connors, wanting to return the favor of helping him against Strong, raided Ed Bolden's Hilldale Daisies team. Bolden saw little choice but to team up with Foster's nemesis, Nat Strong. Within days of calling a truce with Strong, Bolden made an about-face and signed up as an associate member of Foster's Negro National League.