Since an epipen requires a prescription, and the doctor would be writing that prescription for you, I believe it would be against the law for you to use it on anyone besides yourself, including your own children. I personally would not risk the liability of giving a drug, which epinephrine is, to anyone I didn't know well, especially one of the children in the neighborhood. My suggestion would be to keep the liquid and pill form of Benedryl on hand, not quite as fast acting, but it will do in a pinch. While there is still some liability if giving Benedryl to someone else, it's not quite as great as giving them a prescription drug.
Barbara