BuddyPress.org

Not sure I understand your question but I use a variety of methods in sidebar.php to control what manifests.

It can call the sidebar widgit area under much the same circumstances you describe above it also allows for a number of new custom widget areas that I show on specific directory pages done like this:

<?php if ( BP_GROUPS_SLUG == bp_current_component() && bp_is_directory() ) : ?>

<?php dynamic_sidebar( 'sidebar group page' ) ?>

<?php endif; ?>

Which I think is what you’re referring to? of course you can place anything within that group check doesn’t have to be dynamic_sidebar.