Activity notification of blogposts in group activity stream?

Hello,

We have blogposts imported by your great plugin Autoblog appearing in the site wide BP activity feed now. Fab!
Now, if possible we would like to make it so that when a user creates a new blogpost
it would appear as an item in the activity stream of the group he is a member of and not just his private activity.
Is that possible? I see no "posts" option in the activity filter dropdown, as in site wide.

grateful for any help!
Jan