Problem about AS3 referencing

Hi everyone,
nice to meet you all!

I am a rookie in flash, so please forgive me if I asked anything stupid. :smirk:

I have some movie clips inside other movieclip like:

Scene1
├-----------choice A
│       ├----left menu
│       │   └---- button
│       └----show box
├-----------choice B
└-----------choice c

Is there anything I can do in the AS so that when I press the button in “left menu”, the movieclip in “show box” will play? :puzzled:
Which means…can I back reference something? :smirk:

Thanks!!!