Hmmm i ready don't know, mayby try spraying your in the face with a water spray bottle and telling him a stern NO?
Or try the pebbles in a bottle, that worked for my sisters dog when he kept jumping up people, He no longer does it
everytime he jumped up she used to throw the bottle near him or shake it, and he used to run for it because he did'nt like the sound, so hes stopped.
Maybe that will work with ur dog if he licks or gets near the kids faces? u have 2 say no every time u do this obviously, maybe after a good few shakes of this bottle he might get the idea?
it may not work but again its just a suggestion.