Remember that the children may not know their mother's maiden name and what they do know is not first-hand information. They may think their mother's step-father was her actual father. They may never have met her father and may have a totally "mixed" up version of the name in their head as a result. Or they may be entirely correct about their mother's maiden name. It depends upon a lot of factors, but keep in mind that information children provide about their mother's maiden name is not first hand information.