I grew up in an abusive family with a mother who has severe borderline personality disorder and refuses to get medication or therapy. When I met my mother-in-law, I was naturally very distrustful of her. Mothers were not safe to me, and mothers-in-law were supposed to be even worse!
I tell the children how important it is to have nice manners, and I tell the parents what a joy it is to see a lovely family and that clearly they are good, caring parent. My husband died on active military service, so I was a single parent. I raised my boys to always treat people well, even annoying kids in school, as I told them, you might want a job from their dad or to marry their sister. You never know how a minute being an idiot can affect you in future.