Any substance of abuse in a Suboxone user should be of extreme concern.
That said, a lot of Suboxone users do have ADHD. To simply ignore they have it could make the situation worse. Of course try the non-stimulants first, but if they truly have it, IMHO don't completely close off the possibility of a stimulant. The data goes either way. There's some showing that treating ADHD with a stimulant could reduce further drug abuse, but despite that there's other day going the other way, and I've seen several ADHD people abuse stimulants by either selling it, or only needing X-amount to stabilize but wanting more because at that higher dosage it gets them high.
As for benzos, avoid. Again don't be completely black and white but unlike with ADHD, the best treatments are usually not something's potentially abusable. SSRIs, B-blockers, gabapentin, pretty much anything before using a benzo. There's even less reason to give it, and mixing it with Suboxone raises the risk of respiratory depression.
A big frustration for me when I joined U of Cincinnati was I took over another doctor's Suboxone case load and she liberally gave out benzos and used the Suboxone inappropriately. E.g. patient couldn't sleep because he had sleep apnea-she upped his Suboxone to help him sleep better. Another patient would scream at her for more Suboxone and that doctor caved into the screaming, apparently not knowing what boundary setting was. I had to spend about 2-3 months putting the ship that was in mutiny back on course.
It's far harder to take away something someone already had vs not giving it in the first place. I had dozens of patients, thanks to the above doctor, that already had high amounts of benzos, Seroquel, already with the Suboxone. Several of those patients were not happy and I had to show them data from actual sources such as ASAM and the DEA to show them that I wasn't making up the stuff. .."Why would Dr. X, a licensed doctor, give me Xanax if I'm not supposed to take it with Suboxone?"
In fact, one of the reasons she left U of C was she even told me she couldn't handle her Suboxone patients. I don't know WTF was going on with her. She was an FP doctor that did an addiction fellowship, so that's why she was in a psych dept.
On top of that, the office she used was just dirty gritty dirty with me putting the keyboard upside down (when I took over her office) with pretty much a cupful of boogers, nails and what you falling out of it, and staff members told me she dumped the urine from the drug tests in the coffee room sink.
