I actually stumbled upon 'His Father's Bride' while browsing through some lesser-known romance novels last year, and it left quite an impression! From what I've dug up, there doesn't seem to be a direct sequel, but the author has written other works with similar themes—melodramatic family conflicts and forbidden love. If you enjoyed the tension in that story, you might want to check out 'The Thorn of Rosewood' or 'Legacy of Secrets,' which explore tangled relationships in aristocratic settings.
That said, I did hear whispers in some reader forums about a potential spin-off focusing on the younger brother's perspective, but nothing official has been announced. Sometimes authors drop hints on their social media before confirming projects, so keeping an eye there could pay off. Until then, diving into the author's backlist might satisfy that craving for more scandalous, emotionally charged storytelling.