Seconding Toodlepip. And adding that I don't think Immagamma wanted advice. I think she wanted "sympathy" and head patting. Grandparents need to realize that the world has changed. Their access to grandchildren is through the parents, and it's only as stable as their relationship to the parents. The relationship with the parents is the bridge if you will, between the grandparent's generation and the grandchildren's generation.
I don't know why prior generations don't seem able to wrap their brain around this. When they were parents, I'm betting they wouldn't willingly have facilitated relationships between their own children and people who constantly second guessed them, gave unsolicited advice, or interfered with their parenting. At least not ones that weren't related. In prior generations, often being related entitled you to commit a lot of abuse without ever being challenged. What current generations of parents have learned (often through great personal suffering) is that blood relation does NOT mean you must endure abuse without comment and without protecting yourself.
Yes, I'm using the word abuse. Because that's what it is when you deny someone their autonomy, their personhood, their free will and their self-determination. I think in prior generations there's this odd blind spot where they think accusations of being abusive, or passive aggressive, or overbearing couldn't possibly be true because they LOVE their adult children, grandchildren, etc. They believe that if they feel love towards their family members there's no way they could really HURT them, and thus all these "boundaries", complaining, pushback and attempts to explain must be just a lot of hot air and tantrums over not getting their own way.
My theory currently is that the reason prior generations can't SEE that loving one's family does not prevent you from abusing them is because they were brainwashed into that viewpoint by their own parents. Also, children's viewpoint was not a consideration in prior generations and that could extend well into adulthood. If this treatment was good enough for granny it's good enough for her kids and grandkids too.
Thankfully, current generations are learning/have learned that blood does not excuse bad treatment. In some ways I feel quite sad for the prior generations because what they are left with is that what they had to tolerate (having their parents try to run their lives and raise their kids for them) will no longer be tolerated. On a deep level that probably hurts a lot. It's just that that hurt is NOT AN EXCUSE for continuing to try to steamroll over their children and parent their grandchildren. Nor is it an excuse for continuing to be blind to the damage their attitudes cause.
Some will rage and jump up and down on the bridge till it gets rickety and collapses. Some just stand on the near side and shout curses. Some just walk right out onto it, drop an hand grenade and pray.....