Looks like Michael might be Eugene's father, though you have to careful as the Browne's owned a Castlefarm in co Limerick too.
PRONI Reference : D4151/B/31/1
Title : Lease of lands in Castlefarm from Thomas
Dates : 20 July 1769
Description : Lease of lands in Castlefarm from Thomas Browne, 4th Viscount Kenmare, to Michael Mahony of Cloonagh, Co. Kerry.
Also the following confirms the De Courcy link, plus lots more at
http://www.odonohoearchive.com/a-sketch-of-molahiffe-castle-and-the-manor-of-molahiffe/#_ftn21"In June 1823, Court of Exchequer, Fagan a. De Courcy and others, ‘from 29th September next, the House and Demesne of Castle Farm in the County of Kerry now in the possession of the Defendant, Maurice De Courcy.’ In 1826: Fagan, a. De Courcy and others, ‘Set up and let for three years pending this cause from 29th September next the House and Demesne of Castlefarm in the County of Kerry.’ In 1829: Ellen Fagan, Plaintiff, Maurice De Courcey and others, Defendants, Court of Exchequer, 10 July 1829, ‘Set up and Let for three years from 29th September next, the House and Demesne of Castlefarm in the County of Kerry.’
In 1825, in the Court of Exchequer, Ellen Fagan, Plaintiff, Maurice De Courcey and others, Defendants, ‘Set up to be Let for three years, from 25th March next, the Lands of Molahiffe as heretofore in the possession of Maurice, John, Andrew and Daniel Brien.’ In 1828, the lands were in the tenancy of Daniel Supple Esq. In 1831, the lands of Molahiffe, in the tenancy of Daniel Supple Esq, were let in the matter of Fagan, Decourcy and others."
Also from the Limerick wills index there is:
"Courcey, Mary (widow), Castlefarm, co. Kerry 1798"
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