A parent-in-law is a person who has a legal affinity with another by being the parent of the other's spouse. Many cultures and legal systems impose duties and responsibilities on persons connected by this relationship. A person is a son-in- law or daughter-in-law to the parents of the spouse, who
the father of one's son- or daughter-in-law; that is, the father-in-law of one's son or daughter, or, the father of one spouse in relation to the parents of the other
Bonds between some daughters- and mothers-in-law are sometimes compared to the close. She and my father-in-law are retired and have nothing else to do.