Do I tell my family member I know they are narcissistic and up to nothing good?

[Ghostcushion]

Just go with me on this one. If you think a family member is a narcissist, or very least got some kind of issues with relationships and control how do you handle them? I can’t completely avoid, I’m also not interested in any game, I need nothing from them, not that bothered that they don’t like me (it would have been a nice idea but isn’t going to happen).

How do you handle the fact that they do say things to other family members about me and my relationship (none of it is true). I have to face the other family members and I’m my nice honest self. I would hope that they see me for who I am.

My plan is just to carry on happily with my life and pretend when I have to see them that I don’t know they are as toxic as hell. People have told me to tell them on the sly that I know they are toxic but I can’t imagine this going down well.

I'd just tell other people what I thought about them fairly freely. I don't bother lying. But I'd be just about civil to their face as they don't care what I think about them.
I do have family like this so I know they do not give a shit and are oblivious that they've done anything wrong. No point wasting your breath calling them out. But warn people not to trust them.