public class Foo1 : Foo
{
    public object A1 { get; set; }
    public object B1 { get; set; }
    public object C1 { get; set; }
    public object D1 { get; set; }
    public Foo1() { }
}

public class Foo2 : Foo
{
    public object A2 { get; set; }
    public object B2 { get; set; }
    public object C2 { get; set; }
    public object D2 { get; set; }
    public Foo2() { }
}

public class FooN : Foo
{
    public object AN { get; set; }
    public object BN { get; set; }
    public object CN { get; set; }
    public object DN { get; set; }
    public FooN() { }
}

public class Bar1
{
    public Foo1 Value { get; set; }
    public int Prop1 { get; set; }
    public int Prop2 { get; set; }
}

public class Bar2
{
    public Foo2 Value { get; set; }
    public int Prop1 { get; set; }
    public int Prop2 { get; set; }
}

public class BarN
{
    public FooN Value { get; set; }
    public int Prop1 { get; set; }
    public int Prop2 { get; set; }
}