A while back I asked about unofficial sequels to valid continua, asking if they were to be considered when going on missions. The consensus seemed to be that while the original is canon to the sequel, the sequel is not canon to the original, in some sort of bizarre 'half-and-half' continuum that I guess makes sense.

I'm now asking about what I like to call 'official' unofficial sequels. These are sequels that are written by the author or otherwise approved as being in the same canon by them, but don't really mesh well with the original work. Examples include Dragon Ball GT and Phantom of the Opera: Love Never Dies.

How should these be considered when dealing with badfic for the original, if at all?