The reason why Motochika appointed Chikumamaru, who was an infant, to the heir was that Chikakazu and Chikatada had already succeeded other family lines and that, above all, age differences between two elder sons and Nobuchika's daughter whom Motochika doted were too great to get married.
さらに元親が幼少である千熊丸を世子に指名した理由は、親和と親忠は他の家系をすでに継いでいたことと、なによりも溺愛していた信親の娘を娶わせるには、上の2人では年齢差がありすぎたためともされている。