[F8] Random Positioning

I am loading 3 movie clips at once (via a loop) on the fly at random Y positions, however some are overlapping (obviously i suppose) is there anyway to make each clip aware of the previous clips Y position and make sure they don't over lap?

code:

---

if(cnt < 3)

		{

			tspeed=random(10) + 1;

			i =random(my_xml.childNodes.length)

			_root.createEmptyMovieClip("container"+n, _root.getNextHighestDepth());

			_root["container"+n].createEmptyMovieClip("image"+i, this.getNextHighestDepth());

			_root["container"+n]._x=-30;

			_root["container"+n]._y=random(300);

....

---

Is what I'm currently using to create the clips

Thanks in advance.