Hi at all

I would like adding the rest of the supernatural creatures in the game to the supernatural menu in CAS. The problem is that I've never done anything like this before, so I don't have much of an idea where to start and how to achieve the goal "Create all Occult Creatures in CAS". It was disappointing from the start that Maxis only added the Genie to the selection, ignoring all the others. For Meersims and others, all settings are already included in the CAS (Fins settings i.e.), the only thing missing is the appropriate selection in the list to create a Meersim, Plant Sim or others. I mean, Supernatural also gets the Genie's data from Showtime, doesn't it? Or uses the vampire data from Late Night, if available.
With S3PE I created a package for my project, exported the German and English STBL from Supernatural and put it in an external folder.
However, I didn't even find the CAS icons of the supernaturals in the package files of Supernatural.
Can someone perhaps explain to me what I need to do and in which direction I need to look in order to be able to start my project?

Question by side: Why does an entry for the Imaginary Friend appear in the STBL for Supernatural?

Yeah it is very likely a core thing to add that, as nice as it would be to add them and others they neglected to add. They teased us with elves in Dragon Valley but they aren't a lifestate, they just added pointy ears