Вы можете использовать этот код или адаптирован для работы в вашем случае, надеюсь, его работа ..
Добавьте его в свою функцию. Php
add_filter( 'woocommerce_product_related_posts', 'woocommerce_get_direct_related_products' );
function woocommerce_get_direct_related_products() {
global $woocommerce, $product;
// Related products are found from category
$cats_array = array(0);
// Get categories
$terms = wp_get_post_terms( $product->id, 'product_cat' );
//Select only the category which doesn't have any children
foreach ( $terms as $term ) {
$children = get_term_children( $term->term_id, 'product_cat' );
if ( !sizeof( $children ) )
$cats_array[] = $term->term_id;
}
// Don't bother if none are set
if ( sizeof( $cats_array ) == 1 ) return array();
// Meta query
$meta_query = array();
$meta_query[] = $woocommerce->query->visibility_meta_query();
$meta_query[] = $woocommerce->query->stock_status_meta_query();
$limit = 5;
// Get the posts
return array(
'orderby' => 'rand',
'posts_per_page'=> $limit,
'post_type' => 'product',
'fields' => 'ids',
'meta_query' => $meta_query,
'tax_query' => array(
array(
'taxonomy' => 'product_cat',
'field' => 'id',
'terms' => $cats_array
)
)
);
}