AGGIORNAMENTO O (REFRESH) DATAGRIDVIEW DA ALTRO FORM

public void ShowForm2(Form2 FRM)
{
this.show;
}

form2 FRM=NEW FORM2();
FRM.ShowForm2(this);

private void button1_Click(object sender, EventArgs e)
              {
                  Form2 frm2 = new Form2();
                  frm2.prova(this);
              }

  private Form frm1;

public void btSalva_Click(object sender, EventArgs e)
        {
            Form1 _frm1 = (Form1)frm1;
           _frm1.TuoTableAdapter.Insert("Prova", "0000", "0000", "000", "0000");
           _frm1.TuoTableAdapter.Fill(_frm1.DataSet.TuaTabella);
           _frm1.dataGridView1.Refresh();
        }

        public void prova(Form frm)
        {
            this.Show();
            frm1 = frm;
        }