I personally use the next code during my Single.php file to seize show another single template file according to exactly what the user is viewing.

<?php
    if (in_category('Portfolio')) {
        include (TEMPLATEPATH . '/single-work.php');
    }
    elseif (in_category('Blog')) {
        include (TEMPLATEPATH . '/single-blog.php');
    }
?>

However , I'm using Child Styles and for that reason it'll attempt to include files in the parent theme rather than the kid theme. How do you have it to incorporate in the child theme rather?

Confusingly make use of STYLESHEETPATH rather than TEMPLATEPATH.

Awesome that actually works great. While I am showing that code though, wouldso would I recieve it show single-blog.php for those child groups of Blog without needing to list all of them such as this:

elseif (in_category('Blog') || in_category('Sub-Blog')) || in_category('Sub-Blog2'))