If you look in the actionscript dictionary there is a command which is usefull in this process.
basically, on a button use;
ActionScript Code:
on(release) {
loadMovie("swf2.swf", _root)
}
If you want it in a certain place on the movie, then you need to load it into a empty MC.
so create a MC (movieClip) don't put anything in it and then put it on the _root and place it where you want the swf to show.
Instance the MC to whatever you like.
then use on a button;
ActionScript Code:
on(release) {
_root.mcINSTANCE.loadMovie("swf2.swf")
}
Simple