![axel668 (inactive)](https://identi.ca/uploads/axel668/2013/7/16/5j9sUg_thumb.png)
pseudo users is how it's implemented in friendica ... problem is, if the group founder closes down his instance the group dies. think for a federated network something like tags would be more feasible, together with a cross site search (which would be a very cool feature on its own) you could just search for all posts containing a (group) tag