renumbered pages with PdfFileMerger.append()

[ThomasWaldmann]

I have an input pdf with page numbers I, II, 123, 124, ... (they are like that because they are the same as in a print publication).

If I just append that as first and only pdf to a Merger, page numbers get renumbered to 1,2,3,4...

Is there a way to keep the original numbers?

(what I want to do right now is just to add some metadata to the pdf and keep everything else unchanged)