Have you ever respectfully stood up to your parents as an adult?

Yes I have, but very respectfully.

No never had any to stand up to.

No, not my parents, but I have had to stand up to my husband's mother. And I did it as respectfully as I could.

I did. Sadly, I was the only one being respectful. When you have narcissist parents, and you refuse to play the role, they get nuclear. I don't regret it, it made no difference to them, but it did give me peace. 

Yep, after watching both parents stagger idiotically thru their adult lives, standing up to them became inevitable, especially after I got married. I tried both respectful and more "assertive" methods. But it didn't solve the problem of their defective personalities.

First, it was too often repeated nonsense about how my marriage wouldn't last, to showing no interest in my children, to pleading to get their overdue bills paid on birthdays and holidays. ---Long story, that.

My parents are on the outside looking in. 800 miles away. Not nice folks. I can't imagine what it would be like if I hadn't stood up to them.

Conversely, my in-laws are marvelous people. Like night and day. 

I've never had to. I would have no problem standing up to them if I felt the need to, but it hasn't come up.

Yes, it was regarding my mother deciding to "punished" my son at a family reunion. She told my wife who came directly to me and informed me. I politely drew a FIRM line in the sand so that there was no confusion as to her role as a grandmother versus our role as their parents.

Then I talked with both my children so they knew they were to let me know if this ever happened again.

No. No need to, but I don't think I  could ever get up the nerve. Too shy.