Since Gosanke acted as a backup bloodline for the shogun family, they necessarily had their own branch domains as a reserve system in order for them to retain their family head, so they had branch families called Gorenshi or Renshi (brothers of prestigious noblemen).
また、将軍家の血筋の予備としての御三家の性格上、御三家自身も当主を絶やさぬように血統の保存装置として支藩を持つ必要があり、御連枝（ごれんし）と呼ばれる分家を持った。