FOUND… sort of… check out the update (9/7/6) to her FAQ

From the FAQ on her site(7/2006)…

5. Will you be writing about the duchess, Georgiana, the mother of all the Knight siblings?

No, sadly. She is an exciting character, true, but she doesn’t cut it for heroine material in my view. This was a (fictional!) woman who hurt too many people in her own selfish pursuit for excitement, and too much of a narcissist to qualify as a true heroine.

On the other hand, I love my readers to pieces, so I listen to what you guys say. This has to do with the surprise waiting for you in HIS WICKED KISS. The Duchess Georgiana lost her chance to be a heroine, but-oh, heck, I’ll just tell you-she gets a fresh start, in a sense, in the form of her beautiful young niece, Georgie, who’s named after her, and who is going to be the heroine of my next book!

I think I can anticipate the next question-the title for Georgie’s book, Book One of the Spice Trilogy, is going to be HER ONLY DESIRE, and we are looking at somewhere around March or April of 2007 for the on-sale date.

all I could find… I agree I wouldn’t have read a book about the mom… also a bit on the book in a new interview with RBL