Seriously I think it's better to be safe than sorry. No hard feelings... but why are you listening to a 8 year old.? If you think he is not safe doing those stunts then by all means help or stop him. If you allow him to do that, what if one day there is no one around to supervise and accident happen, who can you blame? After all you can only blame yourself. You can let his cousin know, didi is still young, may not be able to handle what she can, so try not to let him do these.