I took a look at Griffith's Valuation for Ballywilly (1864) and Mullavilly (1863)
No Donaghy in Ballywilly, but in Mullavilly there was a Thomas Donahy equally sharing a 7-3-0 A-R-P farm with a Richard Lynes.
In my experience, such shared farms invariably indicate a family relationship.
Their landlord was the Count de Salis.