On page 6 of the Deerwester book, there is a section on Earhart Thurwachter's cabin. It says Earhart's son Michael inherited the cabin in 1803. It then casually mentions that in 1855 Michael gave it to his cousin, Moses K. Dierwechter.
If Michael has a cousin, doesn't that mean Earhart would have to have a brother in America? Linking Moses' family to Earhart's family would answer a lot of questions for me.
Here is a little more about what I know: Moses K. Dierwechter lived from December 23, 1832 to June 23, 1897. His parents were George Dierwechter (February 27, 1788 to March 13, 1866) and Elizabeth Moore.
Given the ages, Moses would at best be Michael's cousin's son. However, I don't know who George's father was. I now suspect George's father was Earhart's brother, Johann Georg, who is said to have come along on the ship Janet. He doesn't appear on any immigration records, but certain German records say that Georg and Earhart mentioned going to America.