Hi Sam and Craig/s
I don't know if you've found this already but I just came across an International Genealogical record that seems to link what appears to link our Nappy and John. I've made a screen dump of the info to put under the sources for now to pursue but it seems so likely, I've added the dates to the profiles. Both the Davitts and the O'Malleys seem to have a strong presence in Mayo. The pedigree record is sealed as it has been submitted by a LDS member after 1991.
Kind regards
Clancy