Ignoring Extra Elements in mongodDB C# driver

classes.cs

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

public class PersonWithBirthDate : Person
{
    public DateTime DateOfBirth { get; set; }
}

classes_with_attribute.cs

[BsonIgnoreExtraElements]
public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

public class PersonWithBirthDate : Person
{
    public DateTime DateOfBirth { get; set; }
}