You can run a query against Planning relational tables and get the BR names from there.
FROM hsp_calc_mgr_rules a,
WHERE a.id= b.object_id;
Cameron has quite handy Planning SQL queries here http://camerons-blog-for-essbase-hackers.blogspot.com/search/label/stupid%20Planning%20queries
I've some here http://www.orahyplabs.com/search/label/sql (All are not planning specific though)