She whacked the stick right over before I could stop her,
This is one of the things that we brief our pilots on, so that they can brief their pax properly.
During the ground briefing I tell my passengers that only very small movements are required. Not like a PlayStation at all. In the air I first let them feel me moving the controls, and only then do they get the controls. With my hands very near and initially blocking all excess movement.
Only when they've shown that they can restrain themselves will I let my hands wander further from the stick. But never in a position that I cannot reach the controls quickly, and I also keep my feet on the rudder pedals at all times.
Talking about which, when flying with children make sure they can't reach the rudder pedals, OR that their seat is so close to the rudder pedals that they cannot extend their knees fully and "lock" the pedals. And in the latter case, check they don't have their feet on the brakes when landing.