When and when not to use them in your fanstories.
Ahadi, Kopa, Uru, Zuzu... People seem to think about those semi-canon characters as a completely must-use in every fan story they write, regardless if they actually follow SNA events or not. Let me explain where it went wrong.
Six New Adventures is a series of short TLK/SP prequel stories. Here we have characters like Mohatu, past king of Pridelands, Ahadi and Uru - Mufasa and Scar's parents, Zuzu, mother of Zazu, Kopa, son of Simba and Nala, and some more characters connected to TLK characters somehow. We also learn about Scar's original name - Taka. But they are not Disney's creations, means they are not fully official to The Lion King universe. They are all creations of Alex Simmons, writer of SNA books. This means that all of these characters apply only to stories written in Six New Adventures books. They don't appear in any other official material.
Now what's my point? I often, very often, see fan stories including those characters, but not including SNA events. For example Taka, son of Ahadi, originally (according to Simons' books) get his scar where he was attacked by the buffalo named Boma and his herd. There are tons on theories how Scar get his Scar, but in almost all of them he is still Ahadi's son, Taka. And this is where it's all WRONG! Ahadi, Taka etc. are strongly connected to SNA stories. They are only official to the events written in SNA. So if your fanstory denies SNA events, you could as well use any other fan charater to be Scar's father.
Getting to (pretty obvious) conclusion - any story that does change SNA's events, but still uses it's characters is an alternate universe.