Motonaga supported Sumiyuki HOSOKAWA during the conflict to determine the heir to Masamoto; when it seemed unlikely that Sumiyuki would inherit the family estate, he schemed with Nagatada YAKUSHIJI and Magoshichi TAKEDA and assassinated Masamoto (Eisho Disturbance) to support Sumiyuki as the family head.
政元の後継者を巡る争いで元長は細川澄之を支持していたが、澄之が家督を継承する望みが薄いことを悟ると薬師寺長忠・竹田孫七らと共謀し、同年に政元を暗殺（永正の錯乱）して澄之を当主として擁立した。