Inserting data from two forms into sql table

Question

I am developing a small pos application where user can make payments and save db. Until now I stored data from one form(datagridview, textboxes etc), but now I decided to add one more form (for payments and the change). The idea is that the user call data from db in datagridview(***barcode, qty, name, price, total, vat et***c) , then press the btnpayment(***opens the 2nd form***), then the user give the the required data(give payment), then after clicking the pay button the data from two forms should be inserted into sql table

Now I want to save data from two forms into sql db in same time using same stored procedures.

Before adding the 2nd form I used this code to insert data:

try

{

conn.Open();

foreach (DataGridViewRow row in dtgartikuj.Rows)

{

if (!row.IsNewRow)

{

SqlCommand cmd = new SqlCommand("insertfaturimi", conn);

cmd.CommandType = CommandType.StoredProcedure;

cmd.Parameters.Clear();

cmd.Parameters.Add(new SqlParameter("@nrfatures", int.Parse(txtnrfatures.Text)));

cmd.Parameters.Add(new SqlParameter("@klienti", cmbklienti.Text));

cmd.Parameters.Add(new SqlParameter("@pagesa", faturimi));

cmd.Parameters.Add(new SqlParameter("@nentotali", txttotali.Text));

cmd.Parameters.Add(new SqlParameter("@zbritje", txtzbritja.Text));

cmd.Parameters.Add(new SqlParameter("@totali", totali.Text));

cmd.Parameters.Add(new SqlParameter("@vleratvsh", textBox1.Text));

cmd.Parameters.Add(new SqlParameter("@nrartikujve", lblnumri.Text));

cmd.Parameters.Add(new SqlParameter("@kasieri", lbluser.Text));

cmd.Parameters.Add(new SqlParameter("@koha", DateTime.Now));

cmd.Parameters.Add(new SqlParameter("@barkodi", row.Cells[0].Value));

cmd.Parameters.Add(new SqlParameter("@emertimi", row.Cells[1].Value));

cmd.Parameters.Add(new SqlParameter("@sasia", row.Cells[2].Value));

cmd.Parameters.Add(new SqlParameter("@tvsh", row.Cells[4].Value));

cmd.Parameters.Add(new SqlParameter("@cmimi", row.Cells[3].Value));

cmd.Parameters.Add(new SqlParameter("@totalipcs", row.Cells[5].Value));

cmd.Parameters.Add(new SqlParameter("@vlerapatvshpcs", row.Cells[6].Value));

cmd.Parameters.Add(new SqlParameter("@vleraetvshpcs", row.Cells[7].Value));

cmd.ExecuteNonQuery();

}

}

}

catch (Exception ex)

{

MessageBox.Show("Faturimi deshtoi" + ex.ToString());

}

finally

{

conn.Close();

}

The 2nd form has some textboxes (payments and change). Now upper code I want to put into 2nd form insert button , but don't know how to link two forms together. My question is what should I change in upper code to be able to put in 2nd form insert button, then insert 2 forms in same time