Actually she can sign you in ahead of time the day you plan to visit and then she wont have to wait at the gate. When you arrive they will ask for the driver license of each visitor and make copies of each one and also record the license plate and make and model of the vehicle. This will allow you to enter for up to three days and then she would need to sign you in again if you need more days. We did this at both Vista and Chatham so i am speaking from personal experience.
Don't really know about the under 18 enforcement for family visiting.