Carmilla and NPCC (Patreon)

If you use NPCC, the mod forces the Game to pick an existing Sim instead to generate one for every role. Carmilla needs to be generated, and the mod prevents her from spawning. 

I can't do much, since NPCC works via script. The way to make it work is taking out NPCC, have Carmilla spawn, and then put NPCC back... she'll keep her role this way.

Another way could be placing her in your world before going to the Realm, for this reason, I put Carmilla too in the Gallery (my ID is Trykmi) and she already has all the requirements to be picked by the mod as a Sage, but it's not 100% guarantee that it will.

I'm sure that if you don't have NPCC, the game rarely picks her, it always point to generate a new one before picking an existing one (and whatever Maxis said, it does the same with the other Sages, I tried and failed to have Aine replace Morgyn and despite having the trait and all, she was picked in place of Faba and never became the Untamed Sage).

The Tray files for her are attached to this post too.

HOW TO MAKE YOUR SIM THE SAGE OF VAMPIRIC MAGIC

Make your Sim a Vampire Witch

Use the cheats: traits.equip_trait Zero:trait_MagicSage_Vampire 

The game should pick your Sim as the Sage

HOW TO STOP CARMILLA FROM SPAWNING ALWAYS THE SAME

Put the Zero- VampireWitches_MagicHQ_StopCarmillaSpawning.package attached to this post inside your OVERRIDES FOLDER, keep the main mod inside the mods folder... the game should then replace her with an existing Sim or a random Sim if you remove her from the job. Careful that if you put it in before she's generated, then the game will always generate a random Sim.