If it was fraud, it was likely mail fraud, at least at first. That is to say, the people closest around her would not necessarily have known that she was claimi

If it was fraud, it was likely mail fraud, at least at first. That is to say, the people closest around her would not necessarily have known that she was claiming to be Jeanne - the family only had to have a death certificate issued in Yvonne's name, everything else could have continued as normal. And when she did finally have to publicly assume Jeanne's identity enough time had passed that few people would remember her mother.