I am trying to discover if the following three ladies all born in Uffhaffen, Hesse-Darmstadt, Germany, are related.

Barbara DECKER born 26 May 1830; died 25 Feb 1905 in Dubois Co., IN; married Christian MORGENTHALER.
Maria (Mary) DECKER born 1840; died Indianapolis, IN; married Phillip BRETZ. [Their children were born in Dubois Co., IN]
Christina W. DECKER born 15 Apr 1837; died 20 Apr 1913 in Dubois Co., IN; married George BRETZ.

I found a Barbara & Maria DECKER listed as arriving in NY in 1853 aboard the George Haulbut.