Using binding context with 2 tables in C#

       
 ....
        DataTable dt = new DataTable("One");
        DataTable dt1 = new DataTable("Two");
        DataSet ds = new DataSet();
        private void Form1_Load(object sender, EventArgs e)
        {
            dt.Columns.Add("No");
            dt.Columns.Add("Name");
            dt.PrimaryKey = new DataColumn[] {dt.Columns[0] };
            dt.Rows.Add("1", "A");
            dt.Rows.Add("2", "B");

            
            dt1.Columns.Add("No");
            dt1.Columns.Add("Address");

            dt1.Rows.Add("1", "Local address");
            dt1.Rows.Add("2", "Postal address");
            dt1.Rows.Add("2", "Local address");

            
            ds.Tables.Add(dt);
            ds.Tables.Add(dt1);
            //Relation object
            DataRelation rel = new DataRelation("relation1", dt.Columns[0], dt1.Columns[0]);
            ds.Relations.Add(rel);

            bindingSource1.DataSource = ds;
            bindingSource1.DataMember = "One";

            bindingSource2.DataSource = bindingSource1;
            bindingSource2.DataMember = "relation1";


            textBox1.DataBindings.Add("Text", bindingSource1, "No");
            textBox2.DataBindings.Add("Text", bindingSource1, "Name");
            textBox3.DataBindings.Add("Text", bindingSource2, "No");
            textBox4.DataBindings.Add("Text", bindingSource2, "Address");
        }

        private void button1_Click(object sender, EventArgs e)
        {
            bindingSource1.Position += 1;
        }

        private void button2_Click(object sender, EventArgs e)
        {
            bindingSource1.Position -= 1;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            bindingSource2.Position += 1;
        }

        private void button4_Click(object sender, EventArgs e)
        {
            bindingSource2.Position  -= 1;
        }
       ...