Tomoko, who was the third daughter of Duke Sanetsune TOKUDAIJI, who is the elder brother of the former generation of Kichizaemon, married Koju MITSUI of the Mitsui-Muromachi Family; and because Tsuruko, who was the eldest daughter of the former baron Norimaro Tokudaiji, who was the third son of Sanetsune and started the branch family, that is, the granddaughter of Sanetsune married Takanao MITSUI of the Mitsui-Shinmachi Family, which means Honke of the Sumitomo Family and Honke of the Mitsui Family have quadruple or quintuple Keibatsu, Keibatsu blood connections.
先代吉左衛門友純の実兄徳大寺実則公爵の三女奉子は、三井・室町家の三井高従に嫁いでおり、さらに実則の三男で分家した旧男爵徳大寺則麿の長女鶴子、つまり実則の孫娘が、やはり三井・新町家の三井高直に嫁いでいるので、住友と三井両本家は、四重、五重の閨閥関係にある。