no need to really ever do that, because they are as separate file saves, sequences. If you want to put them in the rest of your movie, play around get them exactly right/export them and then bring them in as complete avi files ready to drop in the timeline where ever you like.
if once upon the timeline you want to change them, just open original save file, change to what you want/export, then open up movie again bring the new avi in, and drop it over the original file you were wanting changed
that was a bit mumbo jumbo, but hopefully you get the drift |