Add faxNumber Schema inside an Organization schema

Hello,

Thank you for contacting Rank Math and sorry for any inconvenience that might have been caused due to that.

Since you asked for the refund of the PRO version the way to add the data is with the following filter:

add_filter( 'rank_math/json_ld', function( $data, $jsonld ) {
    if ( isset( $data['publisher'] ) ) {
        $data['publisher']['faxNumber'] = '0123456789';
    }
    return $data;
}, 99, 2 );

​​​​​​​Hope this helps solve your issues.

Don’t hesitate to get in touch if you have any other questions.