answer from the WP forum for those who might need it...
To change the position of the "Yet Another Related Posts Plugin," in your dashboard area go to Settings->Related Posts (YARPP) and untick all the options given next to the "Automagically display" heading and save.
Next, in your child theme create a duplicate of the template you are trying to edit. (http://codex.wordpress.org/Child_Themes#Template_Files) I'm assuming it's single.php or similar?
In this file find the following code:
<?php comments_template( '', true ); ?>
BENEATH this copy and paste the following:
<?php related_posts(); ?>
Click save and this should place the related posts below the Facebook plugin.