How to communicate between movie clip and stage?

I have a flash file in which I import a SWF into an empty MC like so:

loadMovie("all-egms.swf", mySquare);

In the base file, I have a datagrid and a few other objects.

In the imported SWF, I click on a certain item, and I want to do something to an object in the main flash file - let’s say make the datagrid invisible.

I cannot seem to figure out the proper way to talk to the base object from the swf. I tried looking in the debug to get the object name and referencing it like so:

_level0.dataGridMain._visible = false;

That didn’t work, I also tried parent, which also didn’t work.

 
_parent.dataGridMain._visible = false;

I realize there are other ways to import clips, but I’m on a tight deadline and it has to work this way. How can I send a command to the datagrid, or any other object in the main timeline from that imported SWF?