This sort of problem is more common than most realise amongst young children with ADHD. As most people are aware that exclusion only adds to negative feelings in children and young people reinforcing the idea that they are 'naughty' and unwelcome. I know this because we experienced this with our child and at it's extreme.
What does concern me is of the new principle's view on your brother. If this meeting with parent2parent doesn't pan out or that your brothers exclusion from activities continues. From past experience I would watch the waters at school very closely because things can go down hill very quickly.
Little do these schools know that participating in:
activity exclusions, stand-downs, expulsion from schools refusal from other schools does not assist in the development of the child's self-esteem.
The development of self-esteem is so crucial in ADHD children so they can feel proud of who they are and what they do. Self value and respect gives our children/brothers and sisters the power to believe in their abilities and the courage to try new things. It helps them develop respect for themselves, which in turn leads to being respected by other people.
Unfortunately some educational institutions are failing miserably and illegally (Child Rights). Yet they seem to get away with this frequently >> why? >>
Most parents of children are so down trodden by the behaviours of professionals that they no longer have the energy to fight the system for equality for their child.
If brought out into the arena of the media (transparency) of how many children are being disadvantaged, discriminated, abused injustices within the education system would be appalled.
Everyone has a right to be free from discrimination on any of the grounds, including disability (Human Rights Act 1993).