What Would Miss Manners Say?

Okay, Emily Post acolytes. I have an etiquette question for y'all.

Let's say that you throw a mixed-age party for your son's birthday. Mostly adults, four or five kids. And say, hypothetically speaking, of course, that one of the under-6 guests is rather, um, rambunctious.

What is the host's obligation when confronted with an unruly party guest? Does the host 1) Intervene directly, even if the parent is standing by, mildly observing the path of destruction left in his or her child's wake but not doing anything about it? 2) Ignore the disruptive behavior completely? 3) Gently redirect the guest toward a less populated area and safer activity, even though said distraction has a half-life of approximately 35 seconds?

This obviously has NOT happened to me personally. I'm just wondering.