If you have dates for Ferdinand Herrmann of November 24, 1916, then it might be possible that he is my father. He was born in Hamburg, and Anna is his mother's name. I never knew her as she died in 1954 or 1955 in New York City. I have never found her in any obituaries online. In the 1920 or 1930 Census Robert is listed with the name Cihak in New York City, fwiw.
I don't know if we have any marriage information, but I can ask. Rudolf's wife is still alive.
I know we would be interested in whatever you are able to find. Sorry I can't be of more help.
Carolyn Shaffer (Cehak)