Hi - You must be Beckie's sister - we are Facebook friends.
Regarding Oscar's parents, John Henry (Hy) and Theresa Thranert - I lose them after the 1870 census in Aurora, Indiana. They had Children: Fredrick Oscar, Henry, Jacob Wilhelm. Jemima, and John.
Jacob Wilhelm obtained a passport in Germany to stay there and get married. I suspect the entire family went back with them as they totally disappear from any US records after 1870.
Thanks for contacting me.