Parent and child relationships with swapping depths

1 
function blah(){	
	
	for(var f:int = first; f<last; f++){
		
	
				
	var hold:MovieClip = new MovieClip();
		
	
		addChild(hold);
		mcHolder.addChild(hold);
		
		depthArray.push(hold);
		
		storage[hold]= new Object();
		storage[hold].id = f-first;
		storage[hold].depth = depthArray;
	
		
		
	}
	mcHolder.y = 0;
	mcHolder.x = 100;
	addChild(mcHolder);
	
	
	
}

function hover_on(e:MouseEvent):void{
	var a:Object = storage[e.currentTarget];
	var theId:Number = a.id;   //number of the button that is hovered.
	var theDepth:Array= a.depth;
	
	

   for(var c:int = 0; c<theDepth.length; c++){
	   if(mcHolder.getChildAt(theDepth.length-1) == theDepth[c]){
		   var highestDepth:Object = theDepth[c];
   		}
   }
	mcHolder.parent.swapChildren(theDepth[theId], highestDepth);    // i guess this is the line I'm having trouble with
}

the code is stripped down for the sake of brevity. I’m just trying to show where everything is.

so “hold” is the button and is in a loop. All the buttons are placed in mcHolder.
How do I swap depths within the mcHolder?