This is my mother-in-law's family so I will have to check details with her, but my initial feeling is that this is a different family. What I have been able to find on Frederick William Dornberger Jr. is that he was born in NYC Nov. 5, 1896, one of three children (the others being Simon and Frieda), and died in Los Angeles in 1980. Frieda was my m-in-law's mother and according to Frieda's birth certificate dated 9 Aug., 1900 in Manhattan, her mother's name was Pauline Marie Krumf and her father was Fred Dornberger. Both Fred and Pauline were born in Germany, according to the census records, although my m-in-law says they were from Alsace-Lorraine. In at least one census, Pauline listed herself as being from Colbenz. My m-in-law found a copy of Frieda's wedding annoucement in which Pauline listed her name as Pauline Cloude Dornberger.
Fred and Pauline were in New York in 1900 and 1910. Can't find Pauline in 1920, but both show up in Los Angeles in 1930, Pauline divorced and Fred remarried to a woman named Alice.