Refresh DataGridView in parent window

If you are constrained not to use ShowDialog() handle the Closed event of the child form

 

            Form2 childForm = new Form2();

            childForm.FormClosed += new FormClosedEventHandler(childForm_FormClosed);

            childForm.Show();

 

        void childForm_FormClosed(object sender, FormClosedEventArgs e)

        {

            //Your logic to refresh the DataGridView goes here           

        }

use "ShowDialog()" to show the child form.  when it is closed, run your method to update the grid.