Thank you all for you interest and help. I think, with combined efforts, RootsChatters did indeed find "our" Vogel ancestors. I've been busy with some things that have taken me away from genealogy, but I've been able to spend a few minutes here and there researching.
...Note: All these baptisms seem to be taking place in Zell im Wiesental, but this is ony 2k from Atzenbach.
There is a possible Vogel family with father Bart* and mother Magdalena Grass. Unfortunately thare is no obvious possibility for August(see: https://www.familysearch.org/search/record/results?count=75&query=%2Bsurname%3Avogel~%20%2Bfather_givenname%3Abart*~%20%2Bfilm_number%3A922055 )..."
TreeSpirit's findings helped to find the following:
Ernst Barthlin Vogel, born 17 Jan 1856, baptism 20 Jan 1856, Zell im Wiesental (A. Schonau), Baden, Germany
Parents: Barthlin Vogel and Magdalena Grass
Louisa Johanna Vogel, baptism 25 May 1857, death 14 Apr 1858
Parents: Bartholomae Vogel and Magdalena Grass
Carl Eugene Vogel, born 12 May 1858, baptism 24 May, 1858, Zell im Wiesental, Baden, Germany.
Parents: Bartholomae Vogel and Magdalena Grass
Emilie Vogel, born 9 Apr 1865, baptism 16 Apr 1865, Zell im Wiesental (A. Schonau), Baden, Germany.
Parents: Bartholomae Vogel and Magdalena Grass
Our Vogels (siblings) were: Ernest, Charles, August and Emma (Mrs. Emma Hankle). They lived in various places, including Arkansas and Tennessee; I have numerous American records for them, including census returns. Keeping the above baptisms in mind, I found the following interesting (about our Vogels):
Ernest B Vogel, born 1856, Germany. Died 17 Jul 1900. Source: FindAGrave / Ernest B Vogel, 1900 Tennessee Census
The initial "B" points to the possibility that his parents were Bartholomae and Magdalena.
Emma Vogel, born c1865, Germany; married Unknown Hankle. Possibly this is Emma:
Amelia Henkel died in 1918, Tennessee, age 53 - so born c1865; born Germany as were her parents, father B. Vogel and unknown. Husband: Joseph Henkel.
Was Emma/Amelia really Emilie, daughter of Bartholomae and Magdalena?
I also found an obituary for
August Vogel:
Born 21 October, 1859, Baden, Germany...attended schools "of Zell and at other places"..."learned the trade of machinist"...
http://www.rootschat.com/links/01nwq/ I will double-check my notes to confirm that this man was related to Charles, Ernest and Emma. Note: Among other documents, I have found a copy of a newspaper article from 1892, stating that Charles Vogel, of Wynne (Arkansas), was painting his brother, August Vogel's, house.
Aha! I need to confirm that August was a sibling as I just found this item:
August Vogel, son of B. and M. Vogel...(the rest of the paragraph is similar to the article about his passing.)
http://www.rootschat.com/links/01nwr/I have more research to do, but it does look like our Vogel parents were Bartholomea and Magdalena. Thank you again as your interest and findings encouraged me to continue looking in America. Apologies for the long text.