var child:Object=mySwfLoader;
myEmptyMC.addChild(child);

//this changes it to a new thing because I'm setting child which is already added to the MovieClip to something new
child=new Object();

http://board.flashkit.com/board/showthread.php?p=3903435#post3903435

Create an object that you can load SWF's Into for your addChild

object

ActionScript 3