using System;

​

public class Test {

    public Test Child;

    public string GetName() { return _privateName; }

    private string _privateName;

    public void SetChildName(string name) {

        Child._privateName = name;

    }

}

​

public class Program

{

    public static void Main()

    {

        var test = new Test();

        test.Child = new Test();

        test.SetChildName("Yes!");

        Console.WriteLine(test.Child.GetName());

    }

}