sending variable question

[deride]

sending a variable to main MC that is nested in a MC on a external MC

I want to send a variable from within a MC, on a external MC that
is loaded into my main movie. I have been able to send a variable to my main movie if the varible is on the main of the external SWF

(using code below on button on main, in the external MC)
_parent.tempvar = "externalMC.swf";

(code on main MC to load externalMC.swf)
loadMovie (_parent.tempvar, _root.container3);