Are you sure kids will follow melee dwarves into battle? I've never seen this happen, period, and I had a champion macedwarf with three kids and a baby. Babies always come with the mom (lost one, lost the arm of another) but the kids don't seem to follow.
Not positive about kids, but ever since an Unfortunate Incident with a drawbridge cost me a legendary wrestler, her baby, and her husband I haven't risked it.
But I do know that, with this squad, the kids follow their moms around in a huge pack. And they're all best friends with eachother, moms too, so I figure that when one of them dies I might enter a tantrum spiral.
Patrolling didn't really work in this case. I stationed them 10 squares from the trench, patrolled right by it, and still several dwarves (including kids) walked around the dang trench. Moving the patrol route inward three squares, and moving everyone who still insisted on going around into their own squads fixed it.
BTW, these particular kids are NOT slower than their mothers. Most of the moms aren't champions due to a shortage of Bone Bolts. The kids are doing great, OTOH. The youngest is already Agile and Tough, has novice in all the social skills, and has apparently helped with the harvest a few times. She's about 4.
The best is Tun -- legendary woodcrafter via mood, accomplished grower, great in all social skills, Ultra-Mighty, Unbelievably Agile, and Superdwarvenly Tough. He's 10.
He might eat a besieging gobbo squad for lunch, but he's butt naked so I'm not keen to find out.