You're so right Blue, and that needs to happen young like learning No obviously if they're going grab harmful just a change in tone, "no" shouting no good, it's hard work but they get there in the end. My DIL is sowing what she reaped, laughing when they did something naughty, never implementing something, like get off the worktop then totally ignoring it. They're 4 and 5, and are rampagers, really aggressive to each other she now just shouts continually, they laugh at her there's no respect. Even the health visitor sent s.s round as she tried to do a preschool check on the eldest, and both of them were out of control. They live in Wales, I try to visit every 6 weeks they try it on but I'm firm but loving, I do crafts, take them on train rides just normal things, my Son tries to tell her she won't listen, he is great he started a chart where they earn points and eventually get a little treat. He takes them to the park mini football etc. She won't take advice yet it's got to the point she can't take them to the park on her own as they run off no road sense.
I guess it's worse for B and J with the family dynamics luckily at their age P and J had P's guidence and influence, hopefully it will get sorted soon, but what a future could lay ahead, they could either end up in care, or stay with her and end up getting into all sorts by the time they're teens.