It appears Cornelius, who farmed in Kilbaha, Newtownsandes (Moyvane), was the father of my known ancestor John Shanahan. However I am not yet 100% sure so I have added a caution.
There is another Shanahan family with Kilbaha connections but I have been unable to determine if they are related to Cornelius: Margaret Shanahan married Daniel Connell and lived in Kilbaha. They had at least four children: Patrick (born 1831), Johanna (1834), Daniel (1837) and Mary (1842). Then there is Ellen Shanahan who married a Henry Langan and who had at least two children born in Kilbaha: Mary, born in 1819, and Patrick, in 1823. A Sarah Shanahan, married to a Redmond Langan, had a son named Denis, born in Kilbaha in 1828; and a Mary Shanahan, married to a Thomas Sperane, had at least two children: John, born in Kilbaha 1813, and Thomas, born in 1815, also in Kilbaha. There was a Johanna Shanahan, married to a James Carrig and living in Kilbaha, who had a son named James who was born in 1838. There were two Thomas Shanahans, one who married Brigid Sheehan and who had a daughter name Jane in 1838, and the other who married Brigid Nolan and had a daughter named Mary in 1862. However, we have no evidence to connect this family to ours.
The Shanahan surname is common throughout Munster and the south-east. The Shanahans were a sept of Thomond, an area which covered much of north Munster, but in 1318 they were expelled from the Sixmilebridge area of Co. Clare by Turlough O'Brien and the McNamaras. They were scattered throughout Munster, especially in counties Limerick, Cork and Waterford.