Board Thread:Spoilers!/@comment-27060727-20170915041416/@comment-25375217-20170920172520

LadyTremaine wrote: Is it possible that Zelena will be in this episode? It's very possible. They usually announce new characters shortly before or during the filming of their debut episode, so I would say Zelena has a good chance of being in 707, 708, or both.

It's also possible that they announced her earlier than usual since she's such a fan-favorite. Belle was announced before 703 starting filming, IIRC, even though she was in 704. But that was included in the article.