Lir was the father of Manannan (Manannan Mac Lir). Presumably he would also be the father of Mordack and Hagatha as well.
Behind the scenes
Mac Lir means son of "Lir". Lir meaning "Sea" in Old Irish. He is a sea god in Irish mythology. His name suggests that he is a personification of the sea, rather than a distinct deity. He is named Allód in early genealogies, and corresponds to the Llŷr of Welsh mythology. Ler is chiefly an ancestor figure, and is best known as the father of the god Manannán mac Lir, who appears frequently in medieval Irish literature.