So here's my dilemma:

The player can either go directly to an elevator, or pull a fire alarm, and THEN go to the elevator.

Basically, if you skip the fire alarm, you just go up the elevator.

But if you turn on the alarm, a guy will enter the elevator with you. So how would I use a script to both add text to the elevator page (stating that someone entered) AND add a link to the new page with his dialogue (which isn't present unless you use the alarm)

something like this (it's an in-code example):

// I'm not sure if you can do 'get input' or 'show menu' in the Game Book, but for this example, pretend we can, lol

// 'whatever' Page's scripting ( Page Type: [script] or [script+text] ):

msg ("Go to elevator (1) or pull the fire alarm (2)")
get input {
  if (result = "1") {
    msg ("You go to the elevator")
    player.parent = elevator
    game.choice_X = true
  } else if (result = "2") {
    msg ("You pull the fire alarm and then go to the elevator")
    player.parent = elevator
    game.choice_X = false
  } else {
    msg ("You made the wrong choice, resulting in you getting burned up in the fire!")
    msg ("GAME OVER")
    finish // not sure if the Game Book has this Script/Function or not..
  }
}

<page name="elevator">
// I think this is (one way at least in) how it's done with the Game Book's 'page' Objects:
  <script>
    if (game.choice_x) {
      msg ("You enter the elevator alone.")
    } else {
      msg ("As you enter the elevator, you here someone yelling to wait, which you do, with him rushing inside the elevator with you.")
    }
  </script>
</page>