In 1906, Fælledklubbernes Boldspil-Union (FBU) merged with Kjøbenhavns Boldspil-Union, when they realised that a cooperation was necessary with regard to the future plans for Fælledparken. The football associations in the surrounding areas, Amager Boldspil-Union (founded 1912), Nordre Birks Boldspil-Union (founded 1913), Valby Boldspil-Union (founded 1913) and Nørrebro Boldspil-Union (founded 1916), merged to form Københavns Forstadsklubbers Bold Union (KFBU) in 1916 and after intense negotiations, KFBU became a provisional member of KBU and ultimately in the period from 1921 to 1923 the clubs from Amager, Valby and Nørrebro associations became full members of KBU, while the clubs of Nordre Birk became members of Zealand Football Association (SBU).