When I was in Hahnstätten in August this year to check the church registers there, I found the following entry in the “Marriage Book 1769 – 1718”: Johannes Fillbach was born on 23 Nov. 1780 and died on 1 May 1846 in Hahnstätten. His father was Johannes Fillbach (probably the Johannes Fillbach (ca. 1733 – 1781) who was married to Maria Christine Keyper). Johannes Fillbach was married (3 April 1803) to Anna Catherine Ochs , born on 3 May 1775, died on 16 Jan. 1842 in Hahnstätten. Anna’s father was Johannes Ochs. Does this match with your other data? You can see this line in Ruth Kelly’s Fillbach book on the page entitled “The Fillbach Family in Germany” (bottom line). So, Marie and Elisabeth Fillbach should be sisters of Johann Fillbach, (1809 – 1871). Do you have any more information on them?
Two more entries which could be interesting for you:
On 2 Oct. 1815 Johannes Friedrich Fillbach (son of Johannes Friedrich who had died prior to that date) married Anna Dorothee Scheid. Her father was Johannes Scheid from Oberneisen. Although the death date of Johannes Friedrich Fillbach (22 March 1856) deviates from that in the Fillbach book (1850) I still think that he is the father of the three Fillbach brother who went to America around 1850.
On 10 Dec. 1809 Philipp Fillbach (son of Johannes Fillbach) married Catharina Elisabeth Müller from Kaltenholzhausen. She was the legitimate daughter of daughter of Philipp Müller and had not been married before.
I hope this information is one more piece in your puzzle.