By the book, eat the egg off your face for missing the back-court and count the bucket. OTOH, depending on the attitudes in your league, you can sometimes just straighten out the mess by killing the whole play and giving team B the ball at mid-court. Either way there are lessons for the ref's....
I help run a church league with three age groups covering 8-14 year olds. In the 8-10 year olds I teach my ref's to ignore "dexterity" violations, but call all "mental" violations. For example, every one of them walk when starting or stopping, and the girls often "bunny-hop" before a shot. We ignore this. When they take off running with the ball instead of dribbling, we call it. When they start moving their feet while trying to figure out what to do with the ball, I try to get all those walks called. We call the double dribbles. Three in the key is of course more like 5.
I try to get all the fouls called, because they really learn on this. However, we do ignore contact on the hand or very light arm contact after the ball is away. (You have to do something to not blow the whistle every 2 seconds.)
For the older levels, it is much like junior high where you ignore small travels in order to keep the game moving.
Hope this helps. You can see our notes and rule changes by clicking on the basketball at
http://www.srbible.org.