She believes that he had a brother by the name of Theodore or possibly George Theodore.
She believes she located a ship record for Johanna (Wilhelm's mother) and children located in Germans to America Volume 58, July 1889-1890 page 329. Ship was the Rhein from Bremen to Baltimore which arrived on 13 Feb 1890.
Skibbe, Johanna 57 F W PRZ Balt.
Emma 20 F SERVANT PRZ Balt.
Otto 16 M Lab. PRZ Balt.
Theodor 13 M Lab PRZ Balt.
Now I know that that Wilhelm was in both Chicago and Indiana. Time for a timeline and a check of Chicago Directories.