FacetWP – support for Co-authors Plus

<?php

// Add 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',
            'choices' => array(
                'tax/author' => 'Authors'
            )
        );
    }
    return $sources;
}, 10 );