Regular townies turning into spellcasters?

So, if I tick every premade house/family in the game into My Households or whatever, those Sims won’t show up in the magic realm (unless they already are spellcasters). Is that right? I’ll likely start a new save when I get the pack, but I still don’t wanna see the Landraabs and Calientes pop into magic realm lol It is rather annoying that they made “spellcaster” and npc slot like that though. Instead of just randomizing all spellcasters like they do with vampires.