The mother-in-law/daughter-in-law relationship is one of the most complicated in family dynamics. There can be competition between the women for the affection of the son/husband and power struggles over place in the family.
In an article published in "Family Dynamics," researchers identified that both mothers-in-law and daughters-in-law need to develop communication skills in order to deal with the ambivalent feelings they have toward each other.
Honest communication is critical in establishing a healthy relationship between a mother-in-law and the woman who is married to her son. When the relationship is characterized by dishonesty, the entire family suffers.
Determine If It's Really a Lie
Misunderstandings can often be perceived as lying. The first step in handling a situation in which you think your daughter-in-law might be lying is to determine whether the information is really a lie or just a miscommunication. To do this, ask the question directly. For example: "I thought we agreed that it would be all right for me to stop by without calling. But you told David that I just drop by unannounced. Did I misunderstand you?" By approaching the situation as a misunderstanding, you'll reduce the tension and be able to open the lines of communication.
Determine the Recipient of the Lie
If you find that your daughter-in-law is really lying, then you need to determine the recipient of the lie. Is she lying to you? Is she lying to her husband? If she is lying to you, open communication with her is needed: "I hope that we can get to the point in our relationship where you know that you can be honest with me."
If she is lying to your son, however, the situation can be tricky. If she is lying about something major, such as infidelity or addiction, you'll need to speak with your son privately. If he defends his wife, drop the subject and don't bring it up again. Your role is to alert him to the possibility that his wife is lying and to let him choose how to deal with it. If he does nothing with the information, then he is choosing to ignore it. You should then ignore it too.
Understand the Motivation for Lying
Another factor in handling a lying daughter-in-law is the motivation for the lie. Some daughters-in-law lie in order to make themselves look good or to impress the family. This is different than a lie that is told to hurt someone or to cover up behavior that is inappropriate.
If your daughter-in-law is lying to impress you or other members of the family, then open communication is in order: "I noticed that you said you finished college, but here it says you didn't actually get your degree. I hope you know that we love you no matter what."
If she is lying to hurt someone or to cover up inappropriate behavior, then this is a matter between your son and his wife. Mention the problem, and then drop it.
Establish a Sense of Family Identity
In her doctoral dissertation, Christine Rittenour emphasizes the importance of establishing a sense of family identity in improving the relationships between mothers-in-law and daughters-in-law. This is done through the son/husband encouraging a relationship between his mother and his wife, with particular emphasis on open communication, as well as relationships between grandmothers and grandchildren.