Haven’t been diagnosed w it, also not a parent, but…the approach should depend on the severity, it can really vary. Where it’s minor, perhaps some sort of outside intervention can help, like a parent devoting extra time to sitting with the kid and helping them stay focused and organized. In the absence of that, some sort of councelor or tutor, I’d imagine. For serious cases, I think the only way is for the kid and parent to accept that they’ll likely never excel in a structured academic environment, and to instead encourage other means of growth.