// Workaround for bug that prevents DataGridViewRowCollection.InsertRange
// from working when any rows before the insertion index are selected.
private void InsertRows(int index, params DataGridViewRow[] rows)
{
    System.Collections.Generic.List<int> selectedIndexes =
        new System.Collections.Generic.List<int>();
    foreach (DataGridViewRow row in dataGridView1.SelectedRows)
    {
        if (row.Index >= index)
        {
            selectedIndexes.Add(row.Index);
            row.Selected = false;
        }
    }
    dataGridView1.Rows.InsertRange(index, rows);
    foreach (int selectedIndex in selectedIndexes)
    {
        dataGridView1.Rows[selectedIndex].Selected = true;
    }
}