However, since Yoshimune seemed to die until around 1106, it can not be thought that Yoshinobu, who was born 37 years after his death, became his adopted son.
しかし、義宗は嘉承元年（1106年）頃までには死去したと考えられるため、その37年後に生まれた義信がその猶子なったとは理論上は考えられない。