I am very glad to reply as I would like a little help. So many of the Vetters seemed to marry other Vetters in my line. .Also, I did not do the research on these people and so I have no place to tell you to go to authenticate this information.
I have an Eva Katharina Vetter b 13 July 1819, Mittershausen, Hesse, Germany married to Johann Nicolas Rettig md 29 Apr 1838, Schlierbach, Hesse, Germany. I know nothing about his parents, but hers were Johann Peter Vetter b 10 Jan 1791 d 16 Mar 1856 Mittershausen, Hesse, Germany. Johann Peter married Mary (unknown) b about 1799 d abt 1852. Their children were Eva Katharina (see above), Anna Maria (1821-1823), Anna Katharina (1823- ), Johann Peter (1825-1847), Johann George (1826-1825) md to Anna Margaretha Rettig (1827- ), Peter Vetter (1828-1919 Illinois) md to Eva Katharina Spilger 1834-1908 Illinois), Michael Vetter, my 3ggrandfather, (1830-1889 Illinois) md to Maria Elizabeth Vetter (1834-1888 Illinois), Elizabeth Vetter (1832-1863) and Eva Katharina Vetter (1836). As usually a child's name was not used twice unless the first sibling died before the second same-name child was born, I cannot account tor 2 Eva Katharina Vetters in this family.
Then somewhere in the tree on my 3ggrandmother's family is Anna Maria Spilger (1805 Bonsweiher, Hesse-Darmstadt-1894 Illinois md to Johann Ludwig Vetter (1805 Hammelbach, Starkenburg-1843 Hammelbach.) Anna next married Valentin Muehlfeld came to the US in 1856 where he died and she lived with her children. Her information comes from her obituary Aldeo Times 24 Feb 1894. I was given a copy of this by another person I am in touch with. She lives in Illinois and I live in Arizona, so her information is much better documented.
If you can receive a jedcom and I had an email address I could send it to, I would be glad to send you what I have and if you have proof, or even hints of corrections, I would be very grateful, especially with sources. This whole email is probably overload, for which I apologize, but I hope somehow we can help each other. And it would be very nice to find another relative.