as far as i can remember she was raised as the daughter of the duke, but suddenly the duke's previous wife's brother[?] turns up with a girl who looks exactly like the duke and claims she's his legit daughter and the other one was a fake, she gets executed and regresses
there's some prophecy about the family and being a spirit user where disaster will come if there are two daughters? (i can't really remember it that well) and i think it was revealed that the new daughter was created through black magic and so the og daughter was actually the real one
and it was revealed that someone worked with a mage to turn back time but only one person can keep their memories they chose the og daughter to keep hers rather than keeping it themselves, i can't remember if it was revealed who was the person who turned back time with the mage or not
hope this helps! tbh my memory is pretty patchy too
Forgot the whole plot, someone summarize please