I have been trying to put connections to families. I found this today.
Michigan and Wisconsin, 1830-1900 Marriage Index Gender:The gender of Karl Knab is male. Spouse:Margaretha Lehr Marriage Date:Jan 06, 1842 State:MI County:Monroe
I think he is actuallually "Charles Karl Knab" and as you said his spouse is Margaret.I do not believe they are the God Parents I am looking for,but they are probibly the generation before,The Karl/Carl Knab I am after married as follow's
Karl Knab, Wilhelmina Brunner (Both Single) (Godparent Wilhelmina Knab wife of Karl Knab)
They are the God Parents of: Johann Karl Mann, and his sister Mina Hulda Mann Karl and Hulda Mann are the children of: Johann B. Mann JR. and his spouse Christianna Wilhelmina Brunner. Christianna Wilhelmina Brunner had two sister: Eva Margaretha Brunner who married Johann Leonard Sedelbauer AND Margaretha Sophia Karolina Brunner who married Wilhelm Heinrich Blome.
I am actually trying to fit the Correct Wilhelmina Brunner to the correct Carl/Karl Knab.I wonder if your family is part of this connection.