Events on movieclips under other movieclips?

I have two movie clips added at runtime. For aesthetics, the one NOT listening for any mouse events has to be on top. I have a second clip that gets added beneath the first one; I’m trying to figure out how I can get the one “underneath” the first to listen for mouse events – essentially, I want the “top” movieclip to be “invisible” to the mouse.

Both of these clips are on the same parent clip, if that makes any difference. Clear as mud? I’m sure this should be simple, but Flash has been beating me up all day and my brain is fried. Thanks for any help!