Looking for a book - "Father's Wife"

Hi

I read this book growing up. It was one of the first novels I read - and was fascinating.
Dealt with incest, but it was well written. I remember the title was Father's wife - and dealt with a man marrying a woman, and his two kids (son and daughter) seducing their step-mom.

If anyone has links/knowledge of this book - do let me know.

Probably - 1960-1980 (my guess would be 1970s)

Cheers

Very suspicious.. No Books and Joined yesterday

Eh, normal? Some people do go straight to the forums before cataloging.