I understand how in_category works, for example here's a snippet from my single.php
<?php
$post = $wp_query->post;
if ( in_category('18') ) {
include(TEMPLATEPATH . "/single-cbc.php");
} elseif ( in_category('19') ) {
include(TEMPLATEPATH . "/single-dcc.php");
And that works fine. But how do I make it so that if a user selects both category 18 AND 19 together, their post is given the /single-cbcdcc.php template?
Thanks