I know this isn't what you were looking for, but I think you found David's great-great granddaughter. My great-grandfather was George Haskett (from Killaloe, County Clare) who was married to Anne Ryan. Their son George (my grandfather) married Ann O'Rourke and came to New York. I do not know of any children from that marriage. When Ann died, George married my grandmother Ellen (Nellie) McGrath. My grandfather George had at least one sibling, Martin, who came to New York from Killaloe. George and Nellie had 5 children, George, Mary Ellen, Margaret, Michael and David, my father.
I would love to know how you came by the information about the marriage dates and the name Hastings, which I have heard was a possible name to search. My own information is mainly from public records, because the one aunt who had the information never liked to talk about her family since the children wound up in orphanages after the death of my grandparents. I only found out about my great-uncle Martin after I tracked down the burial plot of my grandparents. Finding his name made the connection to Killaloe through immigration records.
This is exciting news for me and I hope you read this since the original posting was so long ago.
Karen Haskett Wenick