Each time you generate a new child, push it to an array:
var myArray:Array = new Array();
function makeChildren() {
var newChild:MovieClip = new originalMC();
myArray.push(newChild);
addChild(newChild);
}
Then you'll have access to all the generated movieclips to do with as you please. When you need to pause or play them all, just run a for each loop:
for each(var myVar in myArray) {
myVar.pause(); // or myVar.play();
}
Sound like what you're looking for?