(William Newman, in his 3-volume history of the sonata, suspects the younger Rust of claiming proto-Romantic qualities for his grandfather's music that- Newman argues- only existed because of his own editorial work on it. Rosalyn Tureck concurs, see link above, and argues that this corruption of sources may have extended, not just to works by Rust, but even to something known only through a manuscript copy in F.W. Rust's possession, a variant (BWV 903a) of questionable authenticity of Bach's Chromatic Fantasy and Fugue (itself a work whose authenticity is not definitely enough established...))
