A better approach, rather than “I think SIL is a narcissist, and here’s why:” is to engage in conversation with your daughters about SIL’s behavior. Ask them questions about how they feel when she says or does certain things that you are seeing as ‘rude’ behavior. Ask them what they think would be a better way to do or say whatever she is doing or saying that is rude. “Why do you think she said that?” “Do you think it’s nice to talk to —— like that?” “Do you think it’s polite to arrive to Thanksgiving dinner 3 hours late?” “Do you think she should have apologized for that?” “Why do you think she didn’t apologize?” “Why do you think she got mad when—-?” etc.
You don’t say how old your daughters are, but more than likely they have picked up on the fact that their auntie is a little ‘odd’ or ‘off’. If they are very young they might not have the vocabulary to express their perceptions, but you can ask open ended questions and just let them say how they feel about her. If they have been raised in a decent and sane family, rather than a dysfunctional one, they know how to behave and they know what is rude and what is not. They should also know that people can and do make mistakes but how they react to their errors, apologize for mistakes,, and make up for them, is an important part of being human.
In the meantime, model correct behavior for your children and other family members. Don’t let the narc get you upset or make you say or do something you can’t take back. Stay on pleasant terms with whatever family member is unfortunate enough to be married to her. Someday she or he may wise up and decide to end the relationship with the narcissist. If you have been patient and pleasant, you may be a source of strength and a lifeline for them at that time.
Practice the Grey Rock[1] technique. If she finds that you are not an easy target for gossip, backstabbing, or provoking, she will escalate the nasty behavior for a bit for one last try and then give up and ignore you. Which is probably the best outcome you can hope for if you are forced to spend time with her due to family.
Good luck!
Footnotes
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