Re: Groups in blogs
Whilst not strictly what I was looking for there is a partial solution:
wp-config.php
define ( ‘BP_ENABLE_MULTIBLOG’, true );
This will allow Buddypress to run on site wide blogs rather than just on the root domain so in theory you could have a website just create a manual link to their group with their own mapped or sub domain. not sure how well all themes would work with this though, I guess it won’t hurt me to try at some point 
