Ok, the way I generally do it is to add an event dispatch to the sponsor’s button code (in the fla, wherever the sponsor’s button click code is). This will look something like;
dispatchEvent(new Event("buttonClick"));
Then when I add it into my own code I have something like:
swfPublisher.addEventListener("buttonClick", onButtonClick);
private function onButtonClick(e: Event = null): void
{
//do stuff
}
Again it’ll require some experimentation but I find it easier to do that than to mess with trying to get any real cross-communication going!
More info on custom events here: http://www.as3blog.org/2010/03/11/how-to-dispatch-a-custom-event/