creating a listener

I am hoping someone can shed some light....

I have a mc that contains 4 sub movies, each sub movie can be played by clicking a button to start the movie clips animation. What I am trying to do is check to see if either a) all of the buttons have been clicked or b) that all of the sub movies animations are complete at that point I woul like to call a function.

Does anyone have any idea how I can acheive this?

Thanks