"I found, that there was one Henriette in Milwaukee 1890; widowed Frank ..."
There was a Henriette Zimmermann Feller that died in 1912 in Milwaukee. She was the widow of Franz Heinrich Feller, but he died in 1874 (multiple clippings in multiple papers for him). They had a son Oswald (d. 1940).
This information comes from "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.