I think I know who Glamrock Freddy is. And it's all because of one line near the end of the game: "I know what this is. I have been here before. She brought me here. I found myself for the first time when I cleared the path. I did not want to, but I had no choice. Now I have a choice. I have changed. My friends are here. They are so angry... confused... But I can protect you." In Freddy Fazbear's Pizza Place, we find The Blob which had Funtime Freddy, Circus Baby, etc... What if GlamFreddy used to be Gabriel, the one who possessed Funtime Freddy in Sister Location? Do enough thinking, and it could work.