On January 7, 1831, because Masahiro's own uncle Masaharu INUI was sick and had no heir, Masaharu adopted Kusuyata MOTOYAMA (Masahiro's childhood name), the son of Hikoya Shigeyoshi MOTOYAMA (whose previous name was Umanosuke Shigeyoshi INUI), who was the younger brother of Masaharu and had been adopted by Ihei MOTOYAMA.
1830年（天保元年）11月24日実伯父の乾正春が病気で無嗣子のため、正春の実弟で本山伊平の養子となっていた本山彦弥茂良（前名乾右馬之助茂良）の息子である本山楠弥太が、正春の養子となった。