Nested MC's and assigning functions

Right… I have a few rows of movie clips making a menu. Because I will be adding to the number of MC’s I use a variable called “menuitems” and run a FOR loops to assign all of these MC’s onrollOver, onrollOut and onRelease functions. I’m doing this to save having to assign these functions to them individualy (as they are the same functions). Its works fine, but when the MC is released it is told to jump to frame 2, where there will be nested mc’s that need to be able to clicked and rolled over. Because the parent movie has event functions assigned to it they seem to overide them. Is there a way around this? I tried placing a transparent MC on the 1st frame of the movie and trying to assign the onRelease function to the “hotspot” but it doesnt work. Here is my code:

function buildthumbs () {
  for (i=1; i<= menuitems; i++) {	    
	this["a"+i].onRollOver = function () {
	  this.swapDepths (x);
	  new Tween (this, "_xscale", Back.easeOut, this._xscale, 120, 12, false);
	  new Tween (this, "_yscale", Back.easeOut, this._yscale, 120, 12, false);
	 new Tween (this, "_alpha", None.easeNone, this._alpha, 100, 8, false);			

	this["a"+i].onRollOut = function () {
	  this.gotoAndStop (1);
	  new Tween (this, "_xscale", Back.easeOut, this._xscale, 100, 12, false);
	  new Tween (this, "_yscale", Back.easeOut, this._yscale, 100, 12, false);
	  new Tween (this, "_alpha", None.easeNone, this._alpha, 70, 12, false);

	this["a"+i].hotspot_mc.onRelease = function () {
	  new Tween (this, "_xscale", Regular.easeOut, this._xscale, 330, 12, false);
	  new Tween (this, "_yscale", Regular.easeOut, this._yscale, 330, 12, false);
	  a = new Tween (nothing, "_x", None.easeNone, 0, 100, 12, false);
	  a.onMotionFinished = function () {
		b = new Tween (this.logo, "_alpha", Regular.easeOut, 100, 0, 12, false);
		b.onMotionFinished = function () {
		  _parent.gotoAndPlay (2);

I’m not sure if the problem lies in trying to call

this["a"+i].hotspot_mc.onRelease = function()

because when I drop the “hotspot_mc” bit it works fine, but the nested mc’s dont work.

Please help!!!