C#

Form1:

public partial class Form1 : Form
{


    public Form1()
    {
        InitializeComponent();

    }

    private void buttonOpenForm2 _Click(object sender, EventArgs e)
    {
        Form2 frm2 = new Form2();
        frm2.Show();
    }

}


Form2:

public partial class Form2 : Form
{
    public Form2()
    {
        InitializeComponent();
    }

    private void buttonOpenForm3 _Click(object sender, EventArgs e)
    {
        Form3 frm3 = new Form3();
        frm3.Show();
    }
}



Form3:

  public partial class Form3 : Form
  {
    public Form3()
    {
        InitializeComponent();
    }

    private void buttonAddRow _Click(object sender, EventArgs e)
    {
        //What to write here to insert the 3 textboxes values into DataGridView?

    }
}