For example the Book of Hours states that they live outside of the Aurbis (therefore they live in the void) but enter it when there is a Dragon Break.
"...according to the texts, Mnemoli is a wayward child of ANU, one of a pantheon of forgotten deities known as the ‘Star Orphans'... a tribe of gods and goddesses that apparently felt abandoned when the Sun Withdrew from the World-Making. Like many of her siblings, Mnemoli is both confused and delighted with the Aurbis, and explores its five quarters as best she can without the help and regulation of worship, which are not needed (by which I mean, always there) during breakings of the sideways wheel..."
On the other hand if Meridia was a Magna-Ge how would she have left the void to become a Daedra? She couldn't have done it during the Middle Dawn since she was already noted as being a part of the Wheel before that. This suggests that the Magna-Ge inhabit Aetherius. Could someone please enlighten me?