When the father of Ietsugu, Ienobu, died, he told his close advisers, such as Akifusa MANABE and Hakuseki ARAI, that 'if Nabematsu died without an heir, Gorota TOKUGAWA of the Owari Tokugawa family (legitimate son of Owari family head, Yoshimichi TOKUGAWA) or Chofuku-maru (Ieshige) of Kishu should be an heir' (there is another theory).
家継の父・家宣は自らの死に際して「鍋松が嗣子なく薨じた場合は、尾張徳川家の徳川五郎太（尾張当主徳川吉通嫡子）か、紀州の長福丸（家重）を嗣子とせよ」と側近の間部詮房・新井白石らに遺言したと言われる（異説もある）。