preload.php

<?php 
function fwp_preload_facets() {
?>
<script>
(function($) {
    $(document).on('facetwp-refresh', function() {
        if (! FWP.loaded && '' == FWP.build_query_string()) {
            FWP_HTTP.post_id = '<?php global $post; ?><?php echo $post->ID; ?>';
            FWP.facets['product_availability'] = ['americas'];
        }
    });
})(jQuery);
</script>
<?php
}
add_action( 'wp_head', 'fwp_preload_facets', 100 );
add_filter( 'facetwp_template_force_load', '__return_true' );

// My Template Query Arguments

$post_id = (int)(isset($this->http_params['post_id']) ? $this->http_params['post_id'] : null);

return array(
  'post_type' => 'products',
  'posts_per_page' => -1,
  'post_status' => 'publish',
  'order' => 'ASC',
  'orderby' => 'title',
  'meta_query' => array(
     array(
        'key' => 'product_parent_id',
        'compare' => '=',
        'type' => 'numberic',
        'value' => $post_id,
        )
     )
);