It was not a political marriage between families, but was for a private purpose, and it did not differ greatly from thinking that a father and grandfather of a partner was at a similar level as one's own father or grandfather, and brother-in-law was at the same level as brothers.
それは家と家との政略結婚というよりは個人的であり、配偶者の父、祖父はじぶんの父、祖父にも準ずる、義理の兄弟は兄弟に準ずるという範囲で理解していれば大きくは違わない。