I don't remember Scheinfeld ever mentioning oneness or universal consciousness in the book.
He did however state that the other people in your reality exist in your reality because you created them. They are just as real as you are however as they are also creating you in their reality. He doesn't go into depth on that subject but hides behind the "tangled hierarchy" to avoid answering how that can happen.
I managed to come up with a metaphor.
Imagine that we are both playing an online computer game.
You have a character you see as "you" in the game and I have a character I see as "me" in the game.
My computer creates the game world on my screen. In this game world my computer creates "you".
Your computer creates the game world on your screen. In this game world your computer creates "me".
Of course the two game worlds send information between themselves and they try to synchronize so they are as similar as possible but they will never be exactly the same. No matter what transpires in the game my game world is always personally mine even if "me" in the game doesn't really exist and your game world will always be personally yours even if "you" in the game don't really exist.
This way we can both create one another without running into a paradox.