His full brother was Fearghal and his half-brothers were Brian Caech, Tighearnán, Maol Sheachlainn Dubh, Feidhlimidh Mág Samhradháin, the First a later chief of the clan, Tomás Óg, Brian, Domhnall ‘Bernach’ Mág Samhradháin a later chief of the clan, Donnchadh (who was Tánaiste of the clan and died in 1486) and Toirdealbhach.
The Annals of the Four Masters for 1459 state- The spoils of Magh Slecht were seized on by Maguire (Thomas Oge); and Ballymagauran was burned by him on this occasion.
The Annals of Loch Cé for 1460 state- Mac Samhradhain died, i.e. Eoghan.
Eóghan's wife was Nuala, daughter of Lochlann O'Rourke, the King of East Breifne O’Ruairc from 1435 to 1458.
His sons were Éamonn Mág Samhradháin a later chief of the clan, Cathal, Maghnus, Aodh, Fearghal, Uaithne and Tadhg.