Páidín Ruadh Ó Maol Chonaire, who retained two-thirds of his lands in Ballymulconry in the 1650s, may have been Fearfeasa's brother.
[2] He was one of the authors of the Annals of the Kingdom of Ireland and, with the three other chief writers, was included by John Colgan in the designation Annales Quatuor Magistrorum (Preface to Acta Sanctorum Hiberniæ, p. 7), which has become the popular name of the book.
He is identified by Bernadette Cunningham as the scribe of hand E in the autograph of the Annals of the Four Masters.
Fearfeasa strenuously opposed Tuileagna Ó Maol Chonaire, whose criticisms of the work of the Four Masters prevented its publication in the 1640s.
Fearfeasa was the author of many poems, one of which was Mochean do[d] chuairt a Chalbhaigh, addressed to An Calbhah Ruadh Ó Domhnaill.