/// <summary>
/// add Child to the Data Source
/// </summary>
/// <param name="myChild"></param>
public void AddChild(Child myChild)
{
if (FindChild(myChild.Id) != null)
{
throw new Exception("Child already exist");
}
Mother myMother = FindMother(myChild.MotherId);
myChild.LastName = myMother.LastName;
myXML.AddChild(myChild);
}