Loading/Unloading External .swfs

So I have an .fla with code on it which loads an external swf into a blank movie clip with the instance name box3.

filename = ["2_1.swf", "2_2.swf", "2_3.swf"];
path = "";
i = filename.length;
k = Math.floor(Math.random()*i);
loadMovie(path+filename[k], box3);

That works just fine.

On each of the swfs loaded I want to place a code to unload them and have them replaced (unloading may be an unnecessary step) with a new swf from the array.

I can’t for the life of me figure out how to do it.
I could really use the help of you gifted actionscripters out there.
-Ian