User blog comment:B214/Question and Answers 6/@comment-24098614-20160917201940/@comment-9595671-20160917223540

Actually there is one member of her peerage that's known. She has the Behemoth, the "Magical Beast King of the Earth" on her peerage. That's all we know so not sure what piece he took, so you can make the rest of her group whoever you want.

And not exactly, she did briefly show in Volume 22 to talk with the the others about what they want Issei to do. If anything we just won't see her directly. Plus who knows, maybe Ishibumi will give us an epilogue at the end that shows they all made it back one day if we're lucky.

We honestly won't know what'll happen next, so never say never to an idea. Kinda like the favorite prediction on the final arc's villains being the Malebranch.