private void EditPhoneNumberItem(object sender, EventArgs e)
        {
            PhoneNumber phone = (PhoneNumber)lbPhoneNumbers.SelectedItem;

            if (phone != null)
            {
                PhoneNumberDialog dialog = new PhoneNumberDialog(new PhoneNumber(phone));
                dialog.ShowDialog();

                if (dialog.DialogResult == DialogResult.OK)
                {
                    if (org.PhoneNumbersToAdd.Contains(phone))
                    {
                        org.PhoneNumbersToAdd.Remove(phone);
                        org.PhoneNumbersToAdd.Add(dialog.PhoneNumber);
                    }
                    else
                    {
                        org.PhoneNumbersToEdit.RemoveAll(p => p.Id == dialog.PhoneNumber.Id);
                        org.PhoneNumbersToEdit.Add(dialog.PhoneNumber);
                    }
                    lbPhoneNumbers.Items[lbPhoneNumbers.SelectedIndex] = dialog.PhoneNumber;
                }
            }
        }
        private void btnAddPhoneNumber_Click(object sender, EventArgs e)
        {
            PhoneNumberDialog dlg = new PhoneNumberDialog();

            dlg.ShowDialog();
            if (dlg.DialogResult == DialogResult.OK)
            {
                lbPhoneNumbers.Items.Add(dlg.PhoneNumber);
                org.PhoneNumbersToAdd.Add(dlg.PhoneNumber);
            }
        }