gistfile1.txt

add_filter( 'houzez_property_feed_export_thinkspain_property_data', 'add_new_build_to_ts_xml', 10, 3 );
function add_new_build_to_ts_xml( $property_xml, $post_id, $export_id )
{
    if ( has_term( 'New Build', 'property_label', $post_id ) && !isset( $property_xml->new_build ) ) 
    {
        $property_xml->addChild( 'new_build', '1' );
    }
    
    return $property_xml;
}