[of two families]become related by marriage ? 利用～，兩家勾結(jié)在一起，為非作歹。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
指兩家結(jié)成姻親。Two families are linked up through marriage. become relatives by marriage