@Annb, I'll answer your question about youngest grandson here. He's not been lacking in attention. If anything, I believe there has been an overcompensation in attention while dealing with his brother's anxiety.
He's always been a very headstrong child and is prone to tantrums if he doesn't get his own way. My son was dreadful at always having to have the last word but grandson takes it to a whole new level. It doesn't help that there are limited means to discipline children in school and don't they know it! The root of everything is school. His first 2 years were marred by this other child he knew from nursery days. The manager of the nursery warned the school not to put them in the same class (more than once) but they did. This child was a master at instigating trouble but not getting caught because he adopted a "butter wouldn't melt" look. Trouble is, youngest was so keen to get on with everyone, he kept getting involved but he was getting caught! Eventually, the school twigged the cause of the issues in that class and moved that other child out. He now spends most of his time in a behavioural class and is only in school part time. Moving him led to a good year last year when he got all these certificates and we believed he'd learned good behaviour brings rewards. No such luck! Lockdown seems to have reversed everything. They split one of the classes in their year between the other two, with the result there are now 31 in his class (due to staff shortages). Now we have another child in the class in the same mold as the one that was moved. This one is a mystery to me. To be honest, in my time this child would have been a target for the bullies but, instead, he seems to hold sway over the entire class and dictates who they should play with/sit with and He's telling them don't sit with/play with grandson. He is ending up being isolated but He's making matters worse firstly, by trying too hard to be friends then secondly, lashing out when it doesn't work. We've told the school what is going on but grandson has to learn too that he has to behave as he is the only one getting caught. I've made all the allowances I'm prepared to even although I understand He's young and He's unhappy. His cheek and behaviour with us and his family is off the scale which is why I plonked him down last week and told him quietly and firmly this is how it will be. Basically, if you behave badly and give out cheek you will lose your lolly & program when at my house. It will not be for a set period of time, instead it will be until you can show polite and respectful treatment of others. Do it again, same thing happens. He lost them last week, improved for a day and got them back but then was appalling again. I don't argue with him. He knows the consequences and what is required. He still has a tantrum about it but all he is told is you knew this would happen - no ifs no buts.
The issue at school astonished me. Teachers are not allowed to put a hand on a child except where is becomes necessary to break up a fight if there is a risk of one or more being seriously injured. Our problem last week was grandson took a toy into school which I knew would likely prove troublesome. I questioned it as "I thought you were not supposed to take toys into school?" Got the usual response and it's not worth disagreeing as it would just cause a full blown tantrum while trying to walk the last part to school. Not surprisingly, it panned out exactly as I thought. He used it in class to be deliberately disruptive, refused to hand it over to any teacher and the teachers cannot take it off them as they live in fear of the other type of parent who would be right down to school screaming and the teacher and demanding they are dealt with because they dared to take their little darling's toy away. The other issue was as well as being disruptive he was also refusing to do his work in class.
I had a chat with his teacher and explained to her that I understand the way his mind works. Firstly, his Mum is searching him before he leaves but that child is a master at managing to smuggle things in. It has been made clear to him that if he does take anything in that shouldn't be there it will be confiscated and the teachers have the permission of all of us to do it. Next, if he refuses to work just tell him fine, it will go home with you and you can do it at home. Don't get involved and if he tries to object ignore it. This is another consequence he's been informed of. It's his choice, either you do the work in school or it comes home and you do it as soon as you come in (so it eats into playing etc). I've also told teacher not to remove him from the classroom unless it becomes dangerous but normally any tantrum dies down without attention. On the second day there was no tantrum in school - I got it instead in the car because I was taking them to collect their Mum before I took them home. He wanted to go straight home to play and was told no because I have to collect Mum and you will be doing the work you didn't do in school before anything else.
It's tough, but it is showing signs of working and believe me it is very, very tough not to argue back. I'm working on his brother as well not to argue with him or retaliate. He older and if he retaliates his brother thinks it's OK too.
Sorry it's such a long reply but it pretty much lets you know what we're up against. If we can resolve the discipline aspect in school I'm sure his attitude will change because he is disciplined at home. School has not changed for the better in my opinion!