Coordinates transformation on scaled mc's

Hello,

Let me explain what I’m trying to do first, maybe there is another approach different than mine :

the “quest” is to do a zoom effect on more then one level,

ex: mcOne - on click zooms from 1 to 13 (scaleX - AS3);
mcTwo - is contained in mcOne, but it is scaled on authoring time so when the zoom effect of the mcOne ends, mcTwo will be at 100% (scaleX,Y =1);
-on click on mcTwo - the same action as on mcOne is applied but with different zooming parameters and mcThree is reveald, and so on …

I thought the best way to do this is to hold the movieClips one in other, scale each one on authoring time, and register them with the 0,0 in the point i want the zooming effect to occur.
The scaling will be done only on the “mcOne”, no mather on witch of the other movie clips the user clicks(i use the event.target.name to get the name of the clicked movie clip and with that string i query a XML-file for the zooming parameters.
I found a class for moving the registration point,
but here comes the real problem:

how can I find the x,y coordinates for the clicked MC relative to first MC (the one all other are contained in - the same one the scaling effect is applied to) - so i can move the registration point in those coordinates.
Consider the fact that every mc, but first, is scaled each with different values.

Hope some of you has the patience to read all this because i ran out of options :block: