Maybe one way of deciphering between which Ivory's are which, is determining between Roman Catholic and Church Of Ireland. I might be barking up the wrong tree, but it is possible that any Ivory who descended from anyone receiving a land grant would have a Protestant background. While this is not always the case, any new settlers in Ireland would have to hold Protestant beliefs, many changed religion to hold on to any lands they had or face eviction. Revertin back to Roman Catholic at a later date. But it is a point to bear in mind when doing research. It is a point that certainly retarded my research into the Corr background in my family.