While I do not have children I understand your concerns. I too went looking for alt. treatments for my later-life ADHD diagnosis due to concerns about stim-meds and hypertension. There are a myriad of choices with mostly anecdotal reviews. I already take a mid-level dose of a stim-med. I changed my fish oil 1250 mg to a dose with high levels of EPA and DHA, introduced Inositol 1000mg, ginseng and gingko-biloba to try and squeeze more performance out of my pharmaceutical med. before I considered upping my meds. I do not advocate for any of these necessarily but, I think they made a small to moderate difference during a very active and stressful year and a half of my life. I also read a report, sorry no reference, about Vitamin C interfering with certain ADHD stim-meds. So I stopped taking the extra tablet daily. I do take a multi-vitamin that has enough Vit-C so I was not worried.
All that being said, supplements, because there is little to no peer-reviewed clinical work regarding them as a treatment pathway for ADHD, most clinicians/ MDs / Psychs. are not going to speak to them directly. It will be up to you to do the research and experiment with your child as I did on myself. It took me months of taking one, then another, then in various combinations to determine what, if any, benefit there was to spending an additional $30 – 60/mo. on sups. vs just taking my $10/mo. stim-med. Let me be clear, I never stopped taking my stim-med. I was looking to augment mine naturally.
Don’t be afraid to try, do a lot of reading and take your best guesses. I all honesty, most MDs who prescribe meds for ADHD are doing the same thing, just with pharmaceuticals. They try their best guess for a month or two, depending on the med build up scheme, and wait to see if it has done any good. If yes, up the med until it does harm then back off a notch or try something else.
I will say, for me, the introduction of the Inositol, Ginseng and Gingko did provide me with a needed energy boost that the stim-meds robbed me of by removing the hyperactivity I used to rely on. Of course the hyper-activity was a two-edged sword that usually hurt me in the end. The more natural boost was softer and more manageable.
YMMV 🙂 best of luck.