Mulligans of Clontibret, Co Monaghan

I am looking for information on my Great-Great Grandfather Edward Mulligan and his brother, Rev. James Mulligan. According to Rev. James Mulligan's obituary he was born in the historic parish of Clontibret, County Monaghan in 1848. However, his Ordination Card states he was born on 29th of June 1846. Having lost his father, Rev. Mulligan joined his brother Edward Mulligan in Philadelphia in 1861.  He was ordaned in April 1871.

Edward Mulligan, (James' brother & my great great grandfather) was born in/around 1838 in Ireland. 

Unaware of any other siblings or father's name.  Believe their mother's name was Margaret.