currently i add a custom billing field in woocommerce by 

```
function custom_override_checkout_fields( $fields ) {
     $fields['billing']['billing_phone_new'] = array(
        'label'     => __('Phone 2', 'woocommerce'),
    'placeholder'  => _x('Phone 2', 'placeholder', 'woocommerce'),
    'required'  => false,
    'class'     => array('form-row-wide'),
    'clear'     => true
     );

     return $fields;
}

add_filter('woocommerce_checkout_fields','custom_override_checkout_fields');

```

i need to edit this field value in admin side . Currently i can edit all other values in billing address but this value is not appearing in admin section . I use the following code only for to see the value in admin section .

```
function order_phone_backend($order){
    echo "<p><strong>Billing phone 2:</strong> " . get_post_meta( $order->id, '_billing_phone_new', true ) . "</p><br>";
} 

add_action( 'woocommerce_admin_order_data_after_billing_address', 'order_phone_backend', 10, 1 );

```

I read the documentation <https://docs.woothemes.com/document/tutorial-customising-checkout-fields-using-actions-and-filters/> .
But everything in this document working correct expect billing\_phone/Phone is note see under Custom field . I check the screen option but i already ticked custom field . Other custom field and its value are visible and editable .

How can i edit this value in back end . Please help .