Who diagnosed your kids?
If ADHD medication isn't working, maybe there is more going on than ADHD. I recommend a neuropsychologist evaluation. Sounds way over the top for ADHD to me. As for ODD...that in my opinion is not a useful diagnosis. It doesn't help anything. You need to find out why your kids are acting out so badly and if they can even control it. They probably can't. And just looking for medications, without knowing exactly what is going on, is just a crapshoot. You need more extensive testing to pinpoint exactly what is bothering your children...be it sensory issues, lack of self-control, executive function disorders, autistic spectrum, mood disorders, etc. Stimulants can make many disorders even worse.
Please get a new private evaluation and I recommend a neuropsychologist. And keep us posted. Nobody should have to live like that and it doesn't always get better unless it is treated.