The Lahiff spelling seems to have been most common in Co. Clare. Still, there were Lahiffs in Co. Cork (Aghada district) as early as 1794. I am looking for the father of Edward M. Lahiff, who lived in Chicago and was working as a reporter in the 1890s. His father would have probably have been from Co. Cork, either around Whitegate, Aghada, or Midleton. The elder Lahiff married the deaf sister of my great grandmother Mary Barry, who was from Midleton. Good luck with your search.