Thomas Eustace joined with his cousin James Eustace, Viscount Baltinglass in the rebellion of 1580. He was captured and in 1581 was executed together with his eldest son Christopher Eustace who was only nineteen and died with very great bravery. The forfeited estates were unsuccessfully claimed by Sir Maurice Eustace of Harristown in 1700. The estate at this time included Gaganstown (Yagoestown), Swordlestown, Morganstown and considerable lands in Clane. Younger children of several of the previous generations had married into other branches of the family.

Part of Kerdiffstown, two miles north-east of Naas, with other land was occupied by the Eustaces for more than a century. (The remainder of Kerdiffstown including Kerdiffstown House, was owned by the Kerdiff family, with whom the Eustaces intermarried.) Christopher Eustace of Kerdiffstown, late of Kilussy, was High Sheriff in 1465, 1474 and 1475. He leased Donode castle and its lands from Sir Robert Eustace of Ballycutland (Coghlanstown). By his wife Elizabeth Ashe of Forenaghts he had a son Waldron Eustace who married Margaret, daughter of Lawrence Sutton of Tipper. His son Nicholas, a juror in 1551, married first Margery, daughter of Sir William Wogan, and second Anne Eustace, daughter of 1st Viscount Baltinglass.

Their son Thomas Eustace married Joan Eustace of Mainham who was the daughter of William Eustace, who was High Sheriff of Kildare in 1544 and married Margaret FitzGerald of Allen and died in 1557. (When appointed High Sheriff, William was described as William Eustace of Moone.) William was survived by a son, JAMES, and a daughter, Joan, who married Thomas Eustace of Kerdiffstown.

William Eustace presumably son of Edward of Clongoweswood, held the estates in 1519 and married Margaret Fitzmaurice, with issue: Alexander; Anne who married Nicholas Wogan of Rathcoffey and died 1537; and Eleanor who married John Talbot (dvp 1519), son of Robert Talbot of Belgard and his wife Margaret Eustace of Ballycotelan. Eleanor later married Richard Walsh.

Alexander Eustace, William’s son, married Joan, daughter of Christopher Eustace of Kerdiffstown (High Sheriff 1465 and 1474-5). He died in 1557, leaving a son, WILLIAM and a daughter, Eleanor, who married Gerald FitzShaun FittzGerald of Donore.