Regarding Fiedler's work in Johann Strauss III's orchestra, in her
biography of her father Johana Fiedler says that he toured in the orchestra during the
summer of 1912. That's the only year she lists. If he did it during any other
year it would still probably only have been in the summer, because Fiedler
was a student in Berlin for the rest of the year as well as playing second
violin in the Berlin String quartet (his father played first). The family returned
to Boston for good in 1915, so the summer of 1912 seems to be the only
definite time that Fiedler could have been in any of Strauss's recordings.
Did Strauss make any recordings in the summer of 1912? Is there a
discography of them that gives recording dates? That would be nice to have in any case.