Don't have enough time to refute the merging shit (I am very tired and want to go to bed) but it's easy to refute the idea of Zant warpinf the realm. Links sword glowing doesn't mean anything since the light that powers the sword and makes it glow is still in the sword
when he fights Ganondorf later, it's why he can reflect his attacks (Dunno why the Master Sword can't do that in this game without the light from the Twilight realm but it is what it is I guess).
Again, I don't have enough time to talk about the merging feat but someone else knowledgable about the game can step in if they want (Wanna point out the actual game itself doesn't do a good job of supporting the idea that Zant is just fusing different universes together, at least in a way that it'd scale to his or anyone elses AP, also kinda bad to assume parallel world means universe in every instance it's used just because it happened once in a series that loves to use parallel world to mean just about anything).