The bigger deal is avoiding inheritance taxes. In France at the time (and maybe now?) there was no inheritance tax between spouses, but there is otherwise. The

The bigger deal is avoiding inheritance taxes. In France at the time (and maybe now?) there was no inheritance tax between spouses, but there is otherwise. The theory is that the father sees that his wife is dead and knows he only has so many years, but doesn't want to give the tax man any of his money. So they say "ah no, this is my daughter who has died- my wife is right here beside me". Then when he dies, well it's a spouse inheritance to his "wife".