"Um." Cosima... really isn't quite sure how to handle that particular conversational twist. "Who was it?" is all she can think to ask, because beyond 'not Herian,' she really has no idea and that seems like it might be important.

(She doubts there's going to be a lot of confusion between clones unless Sarah starts actively cloneswapping, but it's not like anyone with eyes will miss that they're related. If someone's got a grudge, it might be good to know ahead of time.)