There might be a bug! So, the "special event" that the game is referring to is the one where the MC learns about how the 1 divided by 0 power, since he uses that in the Zoe, Megan, and the Amy scenes. It's the same event for all three of them.
But, if you just walk up and talk to Zoe or Megan, you can trigger their scenes before you even see the "special event." I had the special event trigger for me after I finished all of Sophie, and then Ellie's scenes. I would suggest maybe loading a save before you do the Zoe and Megan content, try to unlock the special event in the proper order first, and then see if it triggers.