Hidehira urged the brothers, Kunihira and Yasuhira to get along with each other, made Kunihira get married with his own Seishitsu (legal wife), a daughter of FUJIWARA no Motonari and had three of Kunihira, Yasuhira and Yoshitsune write Kishomon (sworn oath) for each of them not to harbor treacherous designs each other.
秀衡は国衡と泰衡兄弟の和融を説き、国衡に自分の正室である藤原基成の娘を娶らせ、各々異心無きよう、国衡・泰衡・義経の三人に起請文を書かせた。