FacetWP + Co-authors plus

functions.php

<?php

// Add the following to your (child) theme's functions.php

add_filter( 'facetwp_facet_sources', function( $sources ) {
    if ( class_exists( 'coauthors_plus') && isset( $sources['taxonomies']['choices']['tax/author'] ) ) {
        $sources['co_authors'] = array(
            'label' => __( 'Co-Authors', 'co-authors-plus-for-facetwp' ),
            'choices' => array(
                'tax/author' => __( 'Authors', 'co-authors-plus-for-facetwp' ),
            )
        );
        unset( $sources['taxonomies']['choices']['tax/author'] ); // remove the duplicate
    }
    return $sources;
}, 10 );

how?