Multisite – sort merged get_posts() queries

Question

You can try the new (4.7+) wp_list_sort() utility function that’s a wrapper for WP_List_Util::sort() that uses usort() or uasort().

Example 1:

Sort by descending post date

$sorted_custom_posts = wp_list_sort( 
    $custom_posts, 
    'post_date', 
    'DESC' 
);

Example 2:

Sort by descending post date and ascending post title

$sorted_custom_posts = wp_list_sort( 
    $custom_posts, 
    [
        'post_date'  => 'DESC',
        'post_title' => 'ASC',
    ]
);

Check the Make post here for more information.