Of course, I know the Witch Cult intends to use Emilia's body as a vessel to resurrect Satella, but I wonder why? Maybe it's the fact she's a half-elf? Does the cult have other plans for her? Does the cult have some ways to contact Satella? And furthermore, did, and does, Satella agree with them?
From the Wikia
Certain people, such as Echidna and Pandora, have referred to Emilia as "the witch's daughter", with Pandora also mentioning that she was of the witch's bloodline after seeing her power, hinting at some sort of connection between the two, though nothing has been explained.