Newbie question about Stacks and Picks in particular

Hello - I import my RAW photos and then almost always modify them, creating a new copy when I do so (that's how I have set up the preferences).

99% of the time I want the new copy to be the pick yet I seem to have to select this manually either my moving the copy in the viewer or selecting it with cmd \.

Is there a way I can get Aperture to automatically make the most recent copy the pick of a stack?

David