I've got a feeling we will have fun with Willow and with both our "mothers". My guess is Daliah, who contacted us and told us she knows the "real" MC (Jacob...), is the real mother of MC and she tells him. Afterward, everyone else will be bang-material...
This way the build-up with Azel, Willow and partially the "real" mom would make more sense as all three of them have some tendencies in their behavior with and towards the MC which lets us suggest there is way more happening in the future and this way the incest-thing won't be a problem anymore while technically it would somehow still be delivered in a mental state.
This would be an unreasonably clever twist for BD, but even a blind chick picks corn every now and then...