Question on How to pass selected rows from one datagridview to another

Good evening. I'm developing a Windownsform application with C # and mySql , I'm having some questions on how to pass data from one datagridview to another. Datagridviews are found in different forms. I have some code already done that I can already pass the selected lines. I use a checkbox to pick the rows and send them to the datagridview via a button. But whenever I choose a new line and send it, the previously chosen codes are always True.

This is the button code for passing the chosen rows:

 for (int i = 0; i <= dataGridView1.Rows.Count - 1; i++)

            {
                if (Convert.ToBoolean(dataGridView1.Rows[i].Cells[9].Value) == true)
                {
                    RecordId = RecordId + dataGridView1.Rows[i].Cells["Codigo"].Value.ToString() + ",";

                    MessageBox.Show("selected Id " + RecordId + "check" + dataGridView1.Rows[i].Cells[9].Value.ToString());
                    // RemoveDuplicate(dataGridView1);

                }

            }

This is the code that loads the datagridview to choose the lines:

 private void carregaDados()
    {
        db = new BDconexao.accessBD();
        dataGridView1.DataSource = null;
        dataGridView1.Rows.Clear();
        dataGridView1.Refresh();

        string connectionString = db.getConnectionString();
        //string query = "SELECT * FROM   protese UNION (SELECT * FROM tratamento_estomat) ";
        //string query = "SELECT id, descricao, codigo, preco_clinica, comparticipacao_perc, comparticipacao_max,comparticipacao_inps,comparticipacao_segurado, total_tratamento   FROM   protese  ";
        //query += "UNION (SELECT id, descricao, codigo, preco_clinica, comparticipacao_perc, comparticipacao_max, comparticipacao_inps,comparticipacao_segurado, total_tratamento FROM tratamento_estomat)";
        string query = "SELECT * FROM ((SELECT id, descricao, codigo, preco_clinica, comparticipacao_perc, comparticipacao_max,comparticipacao_inps,comparticipacao_segurado, total_tratamento FROM protese)";
        query += "UNION (SELECT id, descricao, codigo, preco_clinica, comparticipacao_perc, comparticipacao_max, comparticipacao_inps, comparticipacao_segurado, total_tratamento FROM tratamento_estomat) )";
        query += "AS tb ";

        using (MySqlConnection conn = new MySqlConnection(connectionString))
        {
            using (MySqlDataAdapter adapter = new MySqlDataAdapter(query, conn))
            {
                try
        {
                    //******
                    DataTable dataTable = new DataTable();



                    DataGridViewCheckBoxColumn dgvcCheckBox = new DataGridViewCheckBoxColumn();
                    dgvcCheckBox.HeaderText = "Marcar";

                    dgvcCheckBox.Name = "Marcar";
                    dgvcCheckBox.ReadOnly = true;
                    //dgvcCheckBox.FalseValue = "False";
                    //dgvcCheckBox.TrueValue = "True";
                    dataGridView1.Columns.Insert(9, dgvcCheckBox);

                    //******
                    adapter.Fill(dataTable);

                    for (int i = 0; i < dataTable.Rows.Count; i++)
                    {
                        dataGridView1.Rows.Add(dataTable.Rows[i][0], dataTable.Rows[i][2], dataTable.Rows[i][1], dataTable.Rows[i][3], dataTable.Rows[i][4], dataTable.Rows[i][5], dataTable.Rows[i][6], dataTable.Rows[i][7], dataTable.Rows[i][8]);
                    }
                    dataGridView1.AllowUserToAddRows = false;
                    dataGridView1.AllowUserToDeleteRows = false;

                }

                catch (Exception ex)
                {
                    MessageBox.Show("Error" + ex);
                }

           }
        }
    }

following images to understand the idea:

I would greatly appreciate your help in overcoming this. Thank you all