[of two families]become related by marriage ❍ 利用～，两家勾结在一起，为非作歹。By making use of the relation by marriage,the two families colluded with each other,doing evils.
二姓之好èr xìnɡ zhī hǎo
指两家结成姻亲。Two families are linked up through marriage. become relatives by marriage