When I read this, it reminds me of why I haven't had much of a relationship with my mother over the past year.
It's interesting that I've never really had any grievances with how other people treat my children when they are entrusted to their care for short periods, and I don't think anyone has had any grievance with the way I treat their children either, if any of us are going to do something that we're not sure the other parent will approve of, like letting the girls go somewhere alone, or letting them do something where clothes might get filthy or damaged - we ask each other if it's okay first. There is just a level of mutual respect there and if we know that someone feels strongly about something - we will try to uphold that value. Obviously we all have some differences in our values and our parenting styles, but if you believe your child is safe and well looked after, you don't worry about the nuances and intricate details.
If I did have a grievance though, I would speak about it, say "yes I know my thoughts are different to yours on this, and maybe I'm a little strict, over-protective etc..." and make sure i'm not making them feel like I'm judging their parenting style or values, but asking them to respect my wishes on something"... and I would talk to my children about it too saying that I don't want them to be doing X when they're at Y's house and explain why, and that I will mention it to Y's mum.
But if people deliberately disrespected that, then yes, I would probably stop my children from going over there, or certainly lessen visits, arrange play dates on a neutral territory or whatever... a case of trying not to punish the children because of the acts of their parents.
And things with my mother - well there is no respect for my values and my parenting style, there is no respect for anything I specifically try to address with her, in fact most of the time there isn't even an option to discuss anything, because just the fact that I want to discuss that we have a difference iin parenting styles, no matter how gentle and non-judgemental I try to be, just the fact that I'd prefer her to do somethng differently sparks the "you're trying to say I'm a bad mother rage"...and I will get a whole host of abuse screamed and shouted at me, occasionally even threats to hit me, and obviously I leave.
Nothing gets resolved, no compromise is ever reached, because I'm not permitted to hold a different opinion to hers.
And yes, I can talk to my children and say "you know it's not healthy to eat 5 treats, just choose one thing, at a push take 2 and say you will save one for tomorrow", but there is an adult-child power differential there, and my mother certainly uses it. They get "Don't you want x, I thought you liked it, I bought it especially for you" or "Ignore what mummy says, if you want it just have it" or "well that's the last time I'm buying treats for you, because I get them and then you don't want them", "well, I'm not your friend anymore, you have upset me" or "that's it, I'm never buying you anything again, you are sooo ungrateful" or "that's really naughty, telling me you like something and then not eating it when I get it especially for you, I'm not inviting you round again"...
And this is where I get stuck..
Part of me feels that it is for me to start going again, and letting the girls go with me rather than leaving them alone with her, so that I am the responsible person there, and I am taking care of tem and also setting the example of how to handle my mother - except I'm still not really sure that I know how to handle her.
If anyone else treated me that way, I would not be making a regular slot in my life for them, I would speak to them if I saw them out and about socially, but I wouldn't be welcoming them into my life, and that "inner circle". But then if I take the "ill person" perspective, I could see just how grateful she was, how happy she was to have had that 45 mins together the other day, would I deny an "ill-person" that? No, I wouldn't.
And that's the stuff I need to work on.