Indeed there seems to be confusion regarding the 2 marches ‘Jugend marschiert’ and ‘Die Jugend marschiert mit frohem Gesang’. I believe the second (not used in Hans Westmar) is the superior music, actually a delightful piece as sung by a boy choir.
In any case, regarding Ernst Hanfstaengl, he was known mostly as a composer of marches and fight songs (for his alma mater Harvard University). He is credited for "Oberaufsicht und Musik" in the titles of Hans Westmar. But there is another music credit: "Dr. Becce", for "Musikleitung u-Mustrierung". Musikleitung means conductor, but I am not familiar with the term "Mustrierung". Perhaps someone here can help provide the meaning.
Dr. Becce is undoubtedly Giuseppe Becce, a serious classical musician and long-time composer for German cinema. The quite moving opening theme of Hans Westmar does not sound like the kind of music usually identified with Hanfstaengl. I believe it is possibly written by Becce. Can anyone provide some knowledge of this issue? Thank you. Great forum, by the way!