Use soaps with neem and/or tea tree oil in them as a deterrent and to kill them. If your children are not locked then you can even make a paste with neem powder plus a drop or two of tea tree oil and slather it on their head. Let it set for fifteen minutes and then rinse down the drain. I had to do it on my kids a few times when they were in elementary school. Every other month it was back to the tub with them to slather more sludge on. But you know what? It's a heck of a lot better than the chemical crap in the store that kills people or gives them genetic disorders and immune system failures. Natural all the way, Hippie Moon.
If you'd like to make such a deterrent easy for YOU to use as well as them, make a spray bottle of 1 cup of water + 3 drops neem oil + 2 drops of tea tree oil. Spritz on everyone's hair once a day or at least after shampooing.
Neem oil lasts a long time and it is very potent. Don't have to use much at all. I would suggest not purchasing more neem than what you can use in a year. Like.. an ounce or two at the most of the liquid and no more than six ounces of the powdered herb. I just had to throw out a huge 32oz bottle of oil the other day because it was five years old and I wasn't even a quarter of the way through it. It does go bad after a few years. Replenish your supply on a year basis if you can.
You can get tea tree oil at any drug store, though. By the ounce. Very handy!
I think I've seen neem oil capsules before... those would be very handy, too. You can just break open a capsule and drain the oil out and use one or two as needed.