Responses
I just completely read the story, but it does not get mentioned who left her there, why and if the Duke really is her father or not. The only thing mentioned is, that the female lead is a Human (by Kureha/the antagonist of the Duke), which indicates that she might not be his biological child. But they definitely look the exact same, so who knows.
.. that I forgot if she is really his daughter? Who left her there again? Does it mentioned?