A number of researchers have accepted the theory proposed that Peter was the son of a Jacob Rush and that Peter was twice married. His first marriage to Mary Cowell produced Isaac and Bethuel. His second marriage to Elizabeth Stull produced Charles, Paul, Phoebe and others. This is inaccurate.
The Peter Rush who married Elizabeth Stull and fathered Phoebe, Paul, Charles, etc., is the Peter in Monroe County in 1820. He could not be the father of Isaac as Isaac was born in 1785 and this Peter was born between 1775-1794. Peter Rush who married Mary Cowel is not his father either as this family has been documented and resided in Cuyahoga County, Ohio.
The oldest Rush in census records is Jacob Rush (b 1740-1750) and wife Prudance (as recorded in Monroe County land deed).
Their proven children are:
1. Mary b 1784 w/o Alexander Massie
2. Samuel (in Indiana in 1833)
3. Margaret Culbertson born 1774 in Bedford County, PA.
While lacking documentation, all evidence supports the inclusion of these two as children of Jacob:
4. Jeremiah b 1770-1780.
5. Bethuel 1791-1852
These men were considered possible children, but it appears they may be nephews rather than sons:
6. Peter b 1775-80
7. Isaac b 1785
8. Richard b 1794-1800
The last Monroe County Rush is Elias. He was born in 1796, but is probably not a son of Jacob.
ISAAC'S connection to Lancaster---There is a Rush family in Northampton County, Pennsylvania, who have ties to Lancaster County. This family also has a Jacob and Peter Rush in it and the family is connected to the New Jersey branch that went to Somerset/Fulton. Could this be the missing link?
Could there be a clue in the Covalt family? Bethuel Covalt 1746 NJ - 1822 Tonoloway, Bedford, PA had children: Bethuel, Jacob, Isaac, Rachel, Martha (Jacob Hill), Sarah (Mathias Cowll). The names Bethuel, Jacob, Isaac and Cowll/Cowell stand out as being familiar to Isaac's story. Some of them went to Indiana, which is where Jacob Rush died about 1832. There are Jacob and Peter Rushes in the 1790 census in the neighborhood of Bethuel Covalt. What, if any, is the connection?
This is all theory!