How to access a sprite on a "loaded" swf from parent stage

I am creating a Flash training app that includes a glossary. You click a button and the glossary opens. The glossary loads thus:

var request:URLRequest = new URLRequest("glossary.swf");
var loader:Loader = new Loader()

The glossary has a scrollbar, and that scrollbar has this listener (among other things):

scrollbar.addEventListener(MouseEvent.MOUSE_UP, stopScroll);

Once the glossary is loaded into my app, if I do a MOUSE_DOWN on the scrollbar and then drag the mouse away from the glossary, onto the parent stage, then when I do a MOUSE_UP on the parent stage, I need to dispatch a new MouseEvent.MOUSE_UP event to the scrollbar in the glossary swf.

How do I access the scrollbar of glossary.swf in my dispatchEvent? In other words, in the following code in the parent:

stage.addEventListener(MouseEvent.MOUSE_UP, glossarySBMouseUp);
function glossarySBMouseUp(me:MouseEvent):void {
     xxx.dispatchEvent (new MouseEvent(MouseEvent.MOUSE_UP));

…what’s xxx?