Coffey or Coffee

I am researching family relationships for my grandmother, whose maiden name was Helen Coffey.  Her parents left for the U.S., where they had relatives, in 1880.  Helen's mother- Elizabeth Lynch-Coffey- and, apparently, a younger sister named Mary, died shortly after arrival (possibly on Swinburne or Hoffman Islands- I don't know).  Helen's father died not long after (although I haven't found a solid record of his death, either), and Helen was adopted by a family with the surname Walsh. 

Helen's father, James Coffee, was from Coomavohir Mastergeehy (Dromod Parish); her mother, Elizabeth (Bessie?) Lynch was from Dooira. 

DNA has helped me find some distant cousins in the Coffey family, and others (Shea/Sullivan/Connor/Doherty/Leary/Doyle, most commonly).  It's awfully tricking not confusing some of those who were presumably cousins, with all of the repetition of family given names!