Later Tadatsugu married Princess Usui as his lawful wife, who was a daughter of Kiyoyasu MATSUDAIRA, the grandfather of Ieyasu, and his wife Keyoin, and who was Hirotada's half-sister by a different mother.
後に家康の祖父・松平清康と夫人・華陽院の間の娘で、広忠の異母妹にあたる碓井姫を正室とした。