Heinrich Friedrich Brandes is listed as the father of Heinrich Wilhelm Conrad Brandes in the 1850 marriage record for Wilhelm.
Gustav Brandes is listed as the nephew of Wm. Brandes in a 1902 Perry County Republican article, implying that Gustav's father, Heinrich Dietrich Brandes, is Wilhelm's brother.
Johanna Franke is listed as the stepmother of Henry Brandes in the 1880 Union township census. I infer that she was at some point married to Henry's father, Heinrich Friedrich Brandes. Her surname of Franke is unexplained.