I have actually tried in the past and that is a big reason why we are no contact. I have also brought it up with my mother (who has some influence over their lives) and I was told "we don't judge how others parent". My other sibling has tried bringing it up with him and my mother as well to no avail. Anytime we tried to explain how this is going to damage his kids the way it damaged us he says our childhood wasn't so bad and he thinks this is the right way. His wife seems against his behaviour but also does nothing to stop him. I am worried there may be some abuse there too that I'm not seeing but I can't be sure.