I agree with Mike T. The autographs are atypical. Sorry, Karl B.
I purchased a forged Robert De Niro autograph on eBay in August, 2001. The forgers have been leeching among us for many years now, Karl B. Sorry about your Star Wars: Episode I - The Phantom Menace movie poster. We all have lived and learned in this hobby.
Karl, I'd be happy to look at the Potter material for you.
I am not familiar with any of those autographs. If you post an image of the J. K. Rowling autograph, I can compare it to an exemplar that I have. Otherwise, Pete is a great source. You should consider his offer.