According to another view, it is said that, since Masayuki HOSHINA had been officially admitted to be Hidetada's son and was therefore possible to have the family name 'MATSUDAIRA' in the future (Masayuki himself declined to do so, but his descendants became the Aizu-Matsudaira family), Iemitsu TOKUGAWA, the third seii taishogun (literally, "great general who subdues the barbarians") and Masayuki's older paternal half-brother, coordinated the Masasada's promotion mentioned above to try to make Masasada inherit the Hoshina clan instead of Masayuki.
一説には保科正之が正式に秀忠の子と認められたことにより、将来的には「松平氏」姓を名乗る可能性が出てきたため（正之自身は辞退したが、子孫は会津松平家となる）、正之に代わって正貞に保科氏を継承させるための第3代征夷大将軍・徳川家光（正之の異母兄）の配慮があったといわれている。