.... I have some very overbearing cantankerous relatives.
And like your Dad.
Now.... with my kids, if a person acts like that to them and is mean... I speak up right there. To, that relative. I do it in a calm but stern manner, and not in an arguing manner.
I do this, because my kids need to SEE me and hear me... stand up for them. Too. And also by doing so, they see how things can be handled etc.
Then, I also... tell my kids quite honestly, that yes... some of their relatives are, not the best behaved. I KNOW that & it is not their imagination. So by my telling them... they ALSO know, that I know and that... it is not "them" that is at fault. I also teach them to not take it personally. Some of the relatives, are... or can be, inappropriate or bully like. That *I* know that too. And, they can speak up, TOO.
If an Aunty is overly bossy to them... my kids will actually tell her "I'm going to check with Mommy first, if its okay..." and they do. They stop, her. And by doing so, Aunty has learned, that she cannot bully them. Or me. Or us.
Friends or relatives, certain behaviors upon them... are simply not okay.
And therefore, my kids have learned to "discern" things/situations. Which also translates into school/classmate situations.
My Mom, Grandma... will sometimes say "oh he's such a cry baby... my brother was never like that when he was that age...." about my 6 year old son. In front, of him. She is of the thought, that "boys" should not be "emotional." And it hurts my son's feelings, when she speaks that way of him. It is not, nice. And I, speak up RIGHT there, to her.... and so will my Husband, and tell her stop it. We tell her, she should NOT, compare how she grew up, to our son. ALL children, cry. For whatever reason. And we will not ridicule him for it. It is WRONG.
I don't care if she is the Grandma or a stranger, you do not do that, to my son.
She tends to compare my kids, to each other. And to how she and her siblings were. And this is just wrong.
And I do speak up right there, to her.
And if she gets irked, well so what.
*ETA: with relatives being this way, to me/us/my kids... I do NOT make excuses for them, to my kids. I TELL them, it is WRONG behavior. Kids need to know and learn that. They need to learn and know, that just because someone is your relative or friend... it does not mean, you "can" be mistreated.
I make sure, my kids, learn that and can discern that.