I have a 6-year-old boy who is a real handful. My parents are coming with us, so we will have 4 adults and 3 children in our group, but still...Has anyone heard of any type of electronic "homing device" (like a Lojack for children)? Someone told me there was such a thing as a bracelet that would sound an alarm whenever the child was more than 50 feet from a "home base" grownup, like a virtual tether. A leash is probably going a little too far, but some kind of electronic device would be helpful.