Lost "stage." ability using multiple AS files

When I was using timeline AS3 code these two lines worked:

            stage.focus = username_Txt1;

Now I’m using multiple AS files with packages. Like this:

index.swf -->Main.as --> pg1.as --> pg2.as

the above code is in pg2.as. How do i get it to affect the stage?

Also while I’m at it, how do I removeChild a child created in Main.as from either pg1.as or pg2.as? EG: in Main.as I addChild(this_kid) and in pg1.as I need to removeChild(this_kid)