“wpc_after_shipper_details_metabox” is an action hook that allow to add data or custom fields after the shipper details section.

Copy and paste this sample code to add company name after the shipper details and add it to the theme functions.php file

function my_shipper_details_metabox_field( $post_id ){
    // Get Save post metakey "_company_name"
    $company_name = get_post_meta( $post_id, '_company_name', true );
	?>
        <tr>
            <th><label>Company Name</label></th>
            <td><input type="text" id="_company_name" name="_company_name" value="<?php echo $company_name; ?>" /></td>
        </tr>
    <?php
}
add_action('wpc_after_shipper_details_metabox', 'my_shipper_details_metabox_field');

Screenshot