Searching for my G G Grandfather/Grandmother

I'm searching for my Great G Grandfather, Roger Haggerty (Hagerty), wife Mary and son, John Haggerty, born abt. 1842 and married abt. 1865, where is another question.. My research now shows they were all from Crossmolina in Mayo county.  He was Catholic. John married an Ellen Fleming either in Ireland or on ship, or in New York City-don't know.  First son born in 1866 in New York, named Patrick. John & Ellen had 15 children in all. Lived in Cincinnati, Ohio, Hamilton County. Ellen buried in St. Joseph New Cemetary in Price Hill (Cincinnati) & so is John, buried with Patrick and babies and a married daughter.

Any help, thoughts, ideas will be appreciated.  I can be reached at my USA email:  bvolz_atl@yahoo.com.  Planning trip to Ireland first week of September. It will be a bus tour.

Thanks, Bob