User blog comment:TheWarrior29/Should POTCO be considered canon?/@comment-1999071-20140304034810/@comment-1984959-20140305203149

''Like J Fan said, the book came out after. And I wasn't talking about Beckett, I was referring to the princess and her people. They, or the treasure they hold, are NEVER mentioned.''
 * Exactly. There are also several former Pirate Lords, like Don Rafael and Lady Esmeralda, never mentioned as well. Interestingly enough, at the time At World's End came out, a DVD featurette says that Sao Feng took his lordship from his father - whereas he took the title from Liang Dao, his own brother (also not mentioned onscreen) in one of the prequel books.

I think Joshua covered all the other points well, or to the best of his ability.