His Brother's Child - Harlequin

From Renta: Donna is thrilled when her lover, a younger Italian man, proposes to her. Toni is a little irresponsible, but he can give her the family she's always wanted. But when the two of them visit his family home together to announce their marriage, Donna learns the startling truth: his family home is a mansion! His family is so wealthy, it's like they live in another world. That's when Toni's arrogant older brother, Rinaldo, tries to pay Donna to break off the relationship, convinced that she's a gold-digger. And when he realizes he can't drive Donna off with money...he tries to seduce her!