How to access main timeline from external swf

hello,

my main application is a sprite heres my code:
package {
import flash.display.Sprite;
import flash.display.Loader;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.net.URLRequest;

public class ROOT extends Sprite
{
    public function ROOT()
    {
        var loader:Loader = new Loader();
        loader.contentLoaderInfo.addEventListener(Event.COMPLETE, onComplete);
        loader.load(new URLRequest("file.swf"));
        addChild(loader);
    }
    
    public function traceMe():void{
        trace("traceMe();");
    }
    
    private function onComplete(event:Event):void{
        
    }
}

}

from my external swf (file.swf) contains a shape code:

package {
import flash.display.Sprite;
import flash.events.MouseEvent;
import flash.display.MovieClip;

public class file extends Sprite
{
    public function file()
    {
        var shape:Sprite = new Sprite()
        shape.graphics.beginFill(0xff0000);
        shape.graphics.drawRect(0, 0, 100, 100);
        shape.graphics.endFill();
        addChild(shape);
        shape.addEventListener(MouseEvent.CLICK, onClick);
    }
    
    private function onClick(event:MouseEvent):void{
        MovieClip(this.parent.parent).traceMe();
    }
}

}

when my main app is a MovieClip (extends MovieClip) is working.

but my main app is a sprite i take this message

cannot convert ROOT@16b26df1 to flash.display.MovieClip.

can i change this line

MovieClip(this.parent.parent).traceMe();

to something like this Sprite(this.parent.parent).traceMe();