My great grandfather, James William Davison, was born in County Tyrone, Ireland in 1845. He was the son of William Davison and Margaret Leonard. He served in the RIC for about one year when he was 18 or 19 before he emmigrated to the USA (possibly via Canada). He may have been married to a woman named Margaret when he emmigrated. If so, she would have died shortly afterwards.
William married Anne/Anna Byrne(s)in February 1872 in New York City. Anne/Anna was born in County Monaghan in 1846. I do not know when she emmigrated to the USA.
James died 12 November 1916 in New York City. Anne/Anna died 21 July 1924 in New Jersey.
They had the following children: William (1873-1936)(my grandfather), John (1874-1876), Margaret (1877-1959), Anna (1879-1966), Ellen (1881-1961), Rosetta (1885-aft 1910), Robert (1883-1884).
I know nothing about the Byrne(s)line, other than it originated in County Monaghan, Ireland.