@psychobunny It's more noticeable going up because you'll scroll past and then it'll add them, pushing stuff down, and then scroll you back to where you scrolled.

I think this is plugin territory. In my forum I have several threads where only admins can post updates for users. Not really a discussion topic, more of a change log or mini blog. If posts were to start merging the updates would get tangled. Just one use case, but I'd prefer the core code not to automatically join double posts....or at least make it an option.