I have done a lot of research on the Alt/Aults of Frederick/Washington Cos. MD and Loudoun Co. VA. I think the Elizabeth Ault who married John Compher was related to the MD Alts, but I just can't find the proof. I believe she was Mariah Elizabeth. I don't know if she was the mother of Joseph Compher.
From New Jerusalem Lutheran Church Cemetery Records, Lovettsville Virginia by Mary Hiatt & Craig R. Scott:
R8 Compher Mariah E. wife of John Compher d. May 19, 1862 at 77y 9m 22d
S1 Compher John Sr. b. Dec 4, 1773, d. Apr 24, 1846 at 72y 4m 20d