The Sumitomo Family has extensive connections by marriage with former nobles, particularly with the above-mentioned court noble families, as well as with five of the eleven Mitsui families (including the Mitsui Soryo-ke family and the heir); namely, the Hokke, Nagasakacho, Muromachi, Minami, and Shinmachi families.
この公卿を中心とした旧華族と、三井総領家である、北家、永坂町家、室町家、南家、新町家と実に三井十一家のうち、総領家を含む三井の五家との閨閥の拡がりがある。