I'm afraid I can't be of much help. This is a question that crops up fairly frequently. The Ballymoney McElderry family tree is fairly well researched ( check out the Latter Day Saints genealogy pages) and fairly well established. The McCabe/Webster /John McElderry family appears to come from another line, presumably once linked but leading in a different direction. Our speculation is that the families were once all Roman Catholic but that the Ballymoney branch ' trimmed ' their religious beliefs to suit plantation Ireland . The McCabe line retained their beliefs and went their separate way . I don't think anyone has discovered when this happened. So sorry to disappoint.