You can see some options given as answers here:
Flash AS3 - Wait for MovieClip to complete
Basically I would think you want to have an array and a counter for which one you're on, each time the "playNext" function gets called, you should increment the counter and pull the next movie clip from the array. What this means is the order of elements in the array will dictate the order they play in. Something like:
private var myArray:Array = [mc1,mc2,mc3]; //list all the movieclip instance names here
private var counter:Number = 0; //start off on the first element, arrays in AS3 start at 0
//Play the next clip
private function playNext():void {
//Check that we're not at the end of the list, if so just return/stop
if(counter>myArray.length-1)
return;
//grab the next clip
var curClip:MovieClip = myArray[counter] as MovieClip;
//increment the counter for next time
counter++;
//when the last frame gets hit call this function again
curClip.addFrameScript(curClip.totalFrames-1, playNext);
//play the clip
curClip.play();
}
From your constructor of your Main class you would want to call playNext() once to get things rolling.