
Ok.. I'm confused, did the father have 2 wives?
I mean I simply can't figure out who's this Rowanna Person exactly.. They were two woman's shown ; the one with short curly hair and the woman who have long black hair are they the same person? And this Rowanna person can't give birth so.. Was that fake? Can she actually birth a child? I have so many questions

Contains Spoilers.......
The Duke married twice. His first wife was allegedly unable to have children. This wasn't actually the case she was fertile and pregnant. His second wife, kiera's mother and her grandfather, manipulated the situation and basically bullied and abused her. Even spreading the infertile rumors forcing the Duke to having to divorce her and remarried Kiera's mother. His first wife eventually lost the baby and killed herself making a deal with a demon who possessed the baby's body. Making 'Cosette'

That is not true. And was something Keira's mother and her family spread to defame the first wife whom they harrassed and eventually killed.
The truth is he had two wives, although it implied his marriage to Keira's mother was for political reasons due to her family's status.
I don't think he "divorced" the first wife, he had two at the same time. However, Keira's mother was very jealous of the first wife whom its hinted the Duke actually cared for unlike Keira's mother who was just a political match imposed on.
Keira's mother's family wanted Keira's mother to be the sole wife and Duchess that is why they did what they did because I think the Duke wouldn't divorce her.
This is why in the first life he is seen to have flashbacks of previous and he treated "Cosette" whom he just met far more warmly than he did Keira who looks exactly like her mother.
When she was alive, the first wife would plead with the Duke that the second wife and her family were harassing her and she was scared. Due to political reasons and the Parvis "neutrality" policy, he wouldn't act on her behalf.
When she got pregnant Keira's grandfather hired assassins to kill her, sensing her baby was about to die in desperation and despair (since the Duke wouldn't help her when she pleaded for his protection against Keira's mother's family) she makes a contract with a demon to spare her baby's life in exchange with hers.
Unfortunately, both the baby and the first wife dies. However, the demon still enters the dead baby's body and takes full control. This is the "Cosette" we see.
In my opinion the real villains in all of this is not even the demon possessing the dead Cosette's body but the Duke (who knew Keira was his daughter in the first life) and Keira's mother along with her evil family.
Damn Bennet, I didn't know you were suffering this way