A spelling change can happen for so many reasons. Often theoriginal family couldn't read or write and had no idea how to spell their own name. Sometimes an immigration or church official took it upon himself to spell it how he wished, and it stuck. Sometimes the spelling was based on the way it was pronounced (I've seen a couple of family documents with O'Brien spelled "O'Brine", which would have echoed the pronunciation.) Sometimes it's a simple misspelling on a coupleof documents. Sometimes there's no sense to it at all. I have a cousin whose mother insisted on spelling the name "O'Brian"even though noother family member or document reflects this spelling.(She feels the spelling is more traditional and therefore correct)