If Nobumasa (Nobunaga's eldest son, who was born out of wedlock but later adopted by Nobunaga) became head of the Nobuhiro family, it means that the position of head of the main line of the Danjonojo family was passed to the eldest brother in subsequent generations; because both heirs were treated as legitimate, this adoption is highly probable if the brothers Yoshisato and Hidetsuna actually existed.
祖父の兄弟順、信長庶長子信正が信広の家を相続しているとすると父の兄弟順でも兄系が弾正忠家の嫡流となり、相応に正当性のある措置となることから、義郷、秀綱兄弟が実在したとするとこの養子縁組も行われていた可能性が高い。