I think that there were only 6 Fallen Lords that served Balor at a time. After Shiver died, Ravanna came. So in essence, she was her substitute. But then again The Watcher died in Myth I, or did he not? Forrest explains it well in the delusion section over here, but we are not sure what really happened with him (last time we saw him, he was hanging in many pieces). Or maybe he did die and Shiver took his place. I need to put the pipe down now, or else Forrest will get all over me, heh.
Though in total there were 7, just never at the same time. Like Moagim probably had 2 or 3 of them (Bahl'al, Shiver or The Voiceless One, and maybe The Lurker/Bheil).
I want to hear what others think about this.
