He and his wife Cassidy had a son who would go on to become a Templar agent, though he never told his parents of the Order's existence; the Finnegans' son died under unknown circumstances before 1756.
Sometime between late 1755 and early 1756, the Finnegans were asked by Lieutenant-Colonel George Monro to care for Shay Cormac, a gravely wounded individual. While Shay recuperated in the Finnegan house, he came to know and grow indebted to the couple, and even defended them from local gang members when the criminals broke into their home.
After the bandits fled, Cassidy handed Shay their late son's robes, while Barry retrieved the weapons which Monro's men had found with Shay after he fell wounded off the Davenport Homestead's cliffs and washed ashore. Clothed and armed, Shay went out into the streets to eliminate the gang's headquarters, and returned to the Finnegan household afterwards. Barry and Cassidy left Shay and Monro to discuss their next steps in combating New York's criminals.