I have taken my DS to a sports club for children with a physical disability for a while now, about 5 years, give or take some time for Covid.
The premis has always been that siblings are able to join in, and previously my own DD would join in, but she doesnt attend now. Not many siblings do, but the option is there.
Recently, a new family has started. 2 children, the DD has a similar disability to my son, but uses a walking frame. Her brother also attends and is obviously very sporty. I would say he is about 8 or 9. The issue is he is so good, that he is ruining the game for everyone. So for example, he will play in goal but is able to stop all the goals from going in, or he will play infield, and is able to tackle the ball away very easily, and then belt the goal in over and over. He dominates the whole game and noone else gets a look in.
The volunteers that have run the club for ages have tried to get him to do some skills practice off to one side, ut he always ends up coming back to the main game. Some of the parents, including myself, have mentioned it to his Mum, but she has said that she cant help it if he is competitive.
AIBU to think that she should say something to him and get him to either not join in, or not completely dominate the game.