Responses
Isn't it the other way around? He's passing her off as a relative or cousin and not his actual daughter because he doesn't want anyone to know he had a child out of marriage, but decided to raise her if she could benefit him.
No … sure is his daughter but she is related to another family which would be a spoiler
She's actually his niece or other family member, and the rightful heir to the entire, or at least partial, Modrov fortune anyway. He only passed her off as his child because they had similar features. I assume her noble mother was Count Modrov's older sister.