private void txtBox_Leave(object sender, EventArgs e)
    {
        TextBox textBox = sender as TextBox;
        textBox.Visible = false;

            #region TextBox 1
            if (textBox.Equals(txtBox1))
            {
                //Text Box 1 validation
                //Populating Suggestions for TextBox2
                //Passing focus on Textbox 2
            }
            #endregion
            #region TextBox 2
            else if (textBox.Equals(txtBox2))
            {
                //Text Box 2 validation
            }
            #endregion
     }