Thank you so much Mauriz. Your research, so well documented, has me asking all sorts of questions.
The first is -- would a young Austrian woman from an affluent family have taken paid employment in the 1920s? I think that a marriage date might help us understand more about her role in the firm. I have never read anything about Oliver's (aka Otto) first wife and whether they were divorced or she died.
According to indexes of passenger lists Marianne and Oliver arrived in New York in 1940 via what appears to have a circuitous route as there are entries under both names of them having left the UK in 1940 for Rio de Janeiro. I would have to join one of the genealogical groups to access the shipping lists for further details but I have no doubt about their entry to the US in 1940 as Marianne's maiden name (given as Aufrecht) is listed as well as Oesterreicher.