Do you think your kids need to medicated? They are having some major events happen in their lives which I am sure is affecting their performance and behavior in school. I don't think medication will make that any better. Consistency and stability might do the trick.
Have you open-endly asked the boys what's going on? How they are feeling? If there is anything that upsets them or makes them happy? Maybe just talking to their dad would be helpful. Maybe you and the boys can come up together with an action plan for their school work?
Hopefully once there is a consistent homebase and a consisten schedule, things will start to fall backtogether for everyone.