You want them to lean out when they're only 110-125? You complain that they're tiny yet you say you want them to stay small? Sounds like you need to figure out what you want as a coach and not be contradictory.
If you contradict yourself, your kids simply aren't going to have faith in what you tell them or believe in the system, which as a fellow coach I can tell you is the most important factor. It may not be the best program, but if they believe in it they'll get results providing they put the work in.
That and you could try reading the tons of articles here on T-Nation about nutrition and putting on size.