This is a stretch I know, but here goes:

My mother was a Schmitz.
Her father's (Ray) aunt (Anna Grube) married a Stark (before 1896).
They all lived in Outagamie County, namely Appleton and Apple Creek.

Might there be any connect with your Catharina Schmitz? Catharina (that spelling) appears in several places within the Emmerich (Ray's grandfather) Schmitz family tree.
Plus I have terrible luck tracing the Schmitz family so I'll try at anything.