Did Princess Diana have a secret daughter?

There is no concrete evidence that she did, but there is a book that has been released saying that she did have a daughter named Olivia before William. In which case, William is not the rightful heir to the throne. The book tells that there were several attempts on her life simply because she resembled Princess Diana so much. But no, there is no concrete proof as of yet. But if there is a Princess Olivia, and she does come forward, then there will be turmoil within the royal family.