When a person from a branch family assumed the role of Karo or other retainer post, it meant that the person changed from a relative to a retainer of the master's family, and when there were succession disputes they were not considered to have any claim to heirship.
分家筋で家老職をはじめ家臣の役職に就くことは、主家の親戚から家臣になったことを意味し、主家断絶時の相続権が無くなったと見なされることが通例であった。