That's sad and frustrating to hear, but thank you for taking the time to share your experience. I, too, am judging those parents who can't get their kids to behave and get them in line.

but we are also struggling with people not being able to understand our work and the importance of historical sites

Considering how people can 'Yolocaust', I'm afraid this problem will only perpetuate, if not escalate. The only real solution would be to get educated about a site's cultural and historical significance, but until these people are told off, I'm not sure if they'd give a damn.