she inherit it from her father and family name. they already explain how the inherit work in the first chapters she dealt with her "mother"
also she is a countess, not duchess. it a mistake in the translating
I know she already inherited the title but I was just confused that it became a dukedom of some sort. Anyway, thank you for informing me about the error in translation.
I thought it was simply me, forgetting details.
Wait, I thought Kian is a knight and mercenary. Then, Silla is a countess. How come they're the duke and the duchess?