Could you please be more specific in describing what you need?
But from what I could understand is you are want to load a movie clip which is 50 levels deep on the load of a html page.
If this assumption is correct, then you can do so by using external interface. using external interface load the level 50 movie clip by just calling its instance name
I now gather that by default, swf movies load at level = "0", (zero).
So, would I simply LoadMovieNum all my subsequent swf at level 0 (zero)
to bump the original out and replace?