FacetWP – example of combining results from different queries into a final query

<?php

// Get "NV" articles
$q1_args = array(
    'post_type' => array( 'articles' ),
    'posts_per_page' => -1,
    'facetwp' => false,
    'fields' => 'ids',
    'tax_query' => array(
        array(
            'taxonomy' => 'article-region',
            'terms' => array( 'nv' )
        )
    )
);

// Get all articles
$q2_args = array(
    'post_type' => array( 'articles' ),
    'posts_per_page' => -1,
    'facetwp' => false,
    'fields' => 'ids'
);

$q1 = new WP_Query( $q1_args );
$q2 = new WP_Query( $q2_args );

// return the final query arguments
return array(
    'post_type' => array( 'articles' ),
    'post__in' => $q1->posts + array_diff( $q2->posts, $q1->posts ),
    'posts_per_page' => 10,
    'orderby' => 'post__in',
);