My gr.gr. grandfather's sister's godmother was Mary Croghan in 1861 in Baltimore. Mary was married to Patrick Timothy. Patrick was from Kilbegnet which abuts Killeroran and I have several immigrant ancestors from the Killeroran parish (Kennedy, Naughton, Rafferty, Kane). They all immigrated to Baltimore, most between 1850 and 1860. Probably some connection to the Thomas Creaghan that you have, but don't know how.