I’m not sure I buy that argument. The same argument could be made with any edition of a single work—new cover art, new introduction, and new glossary does not make an edition into a new Expression. It is a Manifestation. An edition with new cover art and introduction is not considered a new aggregate Work. Only when there is significant additional material, such as a critical analysis, is it considered an aggregate work. I think Bob is arguing that the same should be true of series.