I get calls from friends to bring their children or grandchildren to see the trains. As an example, one neighbor called to bring her two grandsons...the picture tells the story of how that visit went. I always let the young children operate the Thomas the Tank...keep the voltage lowered, which also keeps the speed under control...
Of course, they both liked their engineer caps too!
Whenever someone visits...we quickly review the rules, there are only two (2), before heading down to the lower level...goes for adults too!!! So far, haven’t had a problem...
The only exception to the “do not touch” rule...was for a couple that I had invited...he is an Alzheimer's patient...he picked up and inspected a few cars, then relocated them to new locations...he seemed inquisitive and enjoyed his time here while visiting the layout and that’s all I cared about.