Diana's brother Charles, in the middle, has red hair, as does her sister Sarah.
Forget the hair. Buy them some shoulders.
Harry strongly resembles her sister Sarah.
Why would anybody have to "force" Harry to have a DNA test? The Queen or Charles could have gotten Harry's doctor to order a test on the QT any time they liked, or taken him to another doctor they trusted, and Diana wouldn't have known a thing about it (neither would this talking-through-her-hat Suzanne person).
Even if Suzanne Simmons is telling the truth about things Diana told her, why should we trust Diana and her tall tales about Harry and JFK, Jr? She was a liar and manipulator.