In an attempt to strengthen power of O-oku (the inner halls of Edo Castle where the wife of the Shogun and her servants reside), his grandmother Senkoin (Yohime's mother and Ienari's second wife) supposedly intended to make his grandson Yoshiyasu the heir because Iesada TOKUGAWA, the heir to Ieyoshi TOKUGAWA, who was seii taishogun and Yoshiyasu's uncle, was in poor health.
祖母（溶姫の母で家斉の側室）の専行院は大奥の権勢を固めようと、慶寧の伯父である征夷大将軍徳川家慶の世子徳川家定が病弱であるため、自分の孫に当たる慶寧を継嗣にしようとしたといわれている。