Board Thread:General Discussion/@comment-6739926-20150118083555/@comment-25926288-20160427225456

Bot of Solitude wrote: I don't thinks she has? But I could be wrong XD I can't think of a time, other than Zelena's mirror, that she used a mirror when Sidney would not have been in it.

But then, it's also possible that she didn't need him for basic spying XD Yeah, when Cora, Zelena, and Rumple have mirror magic, I'm certain that Regina knows as well.