That's about what I figured, on Illyria and Tara -- Illyria probably could put it together, given the motivation, but somehow I don't see her bothering.

As for Didi, I wanna see a scene where she's all "We're mortal! Isn't it awesome? Isn't pepperoni pizza the most delicious thing there is?" and Illyria is all GROWL GLARE YOU ARE A TRAITOR TO YOUR KIND GLARE. (Of course, Didi didn't give up most of her powers forever. So.)