Hello, Could the Jonathan and Dorothy Gillis that you are looking for be the following?
Jonathan Gillis born about 1769 in Minisink, Orange, NY Dorothy Oldfield born about 1773
Jonathan and Dorothy's children: Sarah Jane Gillis born about 1795 in Minisink George Gillis born 23 Jul 1808 in Minisink and died 16 Feb 1884 in Mound City, Missouri
George Gillis (born 23 Jul 1808) married Elizabeth Dodge and they had the following children: Edward born 1834 Laurang born 1837 Levi born 1839 Mary born 1842 Margaret born 1844 Wayne born 1847 George born 1849 Robert born 1852 Cynthia born 1856 Cordelia born 1859
If this sounds familiar to you, let me know and I can provide further info for you.