Tomonari SUMITOMO's elder sister Takashi married Tadateru, the third son of Viscount Tadabumi TORI, who was the feudal lord of the domain of the former Mibu (30,000 koku); consequently, Tadateru changed his name to Tadateru SUMITOMO through his adoption as a son-in-law by the Sumitomo Family.
住友友成の姉の孝は、旧壬生藩三万石の藩主鳥居忠文子爵三男忠輝（元住友本社取締役）を婿養子に迎えており住友忠輝と改名した。