Have you looked into neurofeedback?
I am a neurofeedback technician and I have personally seen vast improvements in children with ADHD using this therapy. It is a financial investment honestly and there is no way to know how many sessions it will take to see huge gains, but there will be small gains throughout.
I will say that recently I have seen someone reduce their Focalin down to a quarter of what they originally were taking, which also helped with the side effects that they were experiencing from the meds. This treatment will be again a financial investment as most insurances will not cover alternative treatments and an investment of time as it should be done 2-3 times weekly, but one that can change some of the issues that ADHD sufferers deal with throughout their life.
This has been proven to be quite effective in treating ADHD I just wanted to suggest it as an alternative or in combination with meds depending on the severity and what is best for the individual. There are several providers in the KC area, even well known hospitals have clinics that provide this service. Good luck and I hope this may help someone!