Kaethe was living at the same address as Emil in the 1939 census, and - according to her former husband's US Declaration of Intention - had been divorced some 5 years earlier. The most likely explanation for this co-habitation would appear to be that they were father and daughter.

A memorial plaque dedicated to Kaethe's son, Ralph, is to be found in Forest Lawn Memorial Gardens Cemetery, 200 NW 24th Ct, Pompano Beach, Broward, Florida, US. Next to his plaque is one dedicated to Kate Blumengarten, born the same date as Kaethe geb. Nothmann, whom I assume is his mother.