Ok, I am confused. the genre Doujinshi is defined on Manga Updates as being a fan work, but there are some works labeled doujinshi that are by the mangaka of the original work... What makes those doujinshi, and should there be a separate genre for them, as they are very different...

So, i guess i'm mainly asking a question while making a tentative suggestion? o well.

Doujinshi are any self-published works.
Many, but not all, are based upon other works.

The genre description is not accurate.

The definition of doujinshi for MangaUpdates is a published fan-made work that is based on an existing series. For us, an original work is NOT a doujinshi

If any series entry does not reflect the above, then that series entry is wrong and must be changed

A just ruler amongst tyrants