Link to external swf movieclip from main swf

Hello everyone,

I have a main fla, which has some buttons on the stage.
When you click on a button an external swf loads(using loadMovie method) inside container_mc which is an empty movieclip.

On that specific external swf, I have created an empty movieclip called [COLOR=“Blue”]content_mc[/COLOR] which also loads external swfs.

Is it possible to call the [COLOR=“blue”]content_mc[/COLOR] from the main fla?
For example when clicking a button of the main fla, how can I point to content_mc which is part of the external swf?