Is this the right Lucy Ross?
Guessing that most women of that time period were married in the county they lived in, I searched the 1840 population census for Vermilion county, IL. (her 1st marriage to Joseph Burton in Vermilion in 1839)
I found -
Samuel Copeland who was born between 1800-1809
Hamilton Copeland who was born 1810-1819
R G Burton born 1810-1819
These could be brothers and worth investigating.
On Ancestry, a Samuel Copeland born 1800, lived in Vermilion County, IL has parents that are Samuel Copeland 1769-1850 and Anna Hayes 1774-1820
On familysearch.org are some Copeland genealogies-