aside from drugging them
well, drat!, there goes my suggestion....
(1) make sure you are all seated together (check the aircraft seatplan and try to get a 3-bank seat set if there is one)
(2) make sure you have something to help the kids swallow frequently (juice or milk) during climb and descend clears the Euston Station Tubes and relieves pain in the ears)
after that you're on your own...