Need some help with dynamic content

Hey everyone, how are ya all doing? ok going straight to the point.

My movie has several buttons: button1, button2, button3 all these buttons ‘on press’ load external movie called external_window.swf but no content. how do I program in flash MX 2004 so it will load 1 external movie but different content that applys to certain button from different sourse. Its kinda hard for me to explain so I attached a little drawing.

thank you