It is five years on, but in the meantime I have done a lot of family research.
Just to add some more clarification on the discussion about the documents relating to Erich Nath's documents that have been displayed in the thread above: My great grandfather has been residing in Danzig, Wallgasse 3a, from the early 1920ies until 1945, as stated in the DLRG-documents of the Erich Nath in question. Erich Nath has been a nephew of my grandfather.
I have no information where Erich Nath has served as a P.O.W., but given the fact that his documents have found their way to the U.S., one can assume that he must have been captured by the western allies.