@iurie I have added filters that will allow you to modify the template arguments and intercept the results on the Github version, but there is a fundamental problem with this approach. The way the plugin works is that it replaces the entire activity stream of a viewed group with the propagated activity stream. This means that filtering the stream to include only items of type ‘new_blog_post’ and ‘new_groupblog_post’ would result in nothing but new blog post activity items in each viewed group’s stream.
What I think you’re after is a “cherry-picked” approach, such that you have the full activity stream for the viewed group with the addition of items of types ‘new_blog_post’ and ‘new_groupblog_post’ from the parent group (or group that you specify). This is a whole heap more complex and not something the ‘bp_has_activities()’ function offers by default. I’m not sure quite how you’d go about doing that except by diving into the SQL modification filters such as ‘bp_activity_get_where_conditions’ or building some sort of meta query.
Ultimately, all of this may be overkill for your needs. Perhaps you need to rethink your UI instead – you could have a widget on each subgroup’s activity stream page that shows nothing but the blog posts from the specified group. It wouldn’t be exactly what you’re after, but it would at least show the posts to members of the sub-groups.