SFG: I think there might be time for a generation between the first settler and William. The settler fought at the Battle of the Boyne in 1690, so must have been at least 14. He got a grant of land, which suggests he was older. If he married and had children starting in (say) 1692, his child would be 22 in 1714, quite old enough to father William. Alternatively, if he was 14 in 1690, he would be 38 in 1714, still within child bearing range, though getting a little old. Maybe his wife was younger than him.
SFG: Next steps -