"I am looking for information on Kate or Kitty Wenzel ... Her step father was John Wenzel. Her mother was Mary Ann VanHyde ... I would also like to know if she was adopted, or just assumed her step father's name."
You don't mention if you've found the Wenzel/van Hyde marriage. You may find records in Milwaukee County probate indeces around the time of that re-marriage if John Wenzel became Kate's legal guardian. These could be in Kate's name as "minor heir" to settle her deceased father's property. I have read probate records where the mother had to file as legal guardian of her minor children where property was involved.
Mary Ann van Hyde Wenzel may also have had probate work done at the time of her death if there were estate issues.
I've also posted about a possible match of death notices in the German papers for Maria Wenzel (née der Heyde), survived by Joh. Karl Wenzel. There are also fairly early notices for a Martin Wenzel in these papers, but too many John / Johann / Carl / Karl etc. to make a guess there.
"Milwaukee's German Newspapers; an index of death notices and related items" (1844-1950).
Gary Rebholz, compiler/editor
Indexing Milwaukee's German newspapers continuously since 2007... helping family researchers collect evidence of our historic German-American culture.