My Rehfeldt's are from Chicago, Il.

My great grandfather was J.J.Ferdinand Rehfeldt B.18 Mar 1837 D. 2 Nov.1916 Chicago, Il.
My great grandmother was Regina Cecilia Diers/Dierz B.1864 D.27 Jan.1904 Chicago, Il.
They arrived in New York 31 Jul.1885 Port of Departure: Hamburg, Germany Ship Name: California

Ancestry has only been able to verify that they had 5 children.

Wilhelm 1862-1942
Caesar 1864-1933
Ferdinand Jr. 1866-1941
Adolph 1870-1922 (Is my grandfather who came over with Ferdinand and Regina and his sister Alwine).
Alwine 1872-1945

I know that the immigrant family's Port of Departure was Hamburg,Germany but I'm trying to find out exactly where the family actually "originated" from. Ancestry couldn't verify that they "originated" from Mecklenburg, Germany. Do you have verification that they actually did "originate" from Mecklenburg, Germany?

Could you please give me the names and dates of births/deaths for the other 8 children?

Regards