Don’t forget about that Joseph Misfud character. He was supposedly in on the dossier, I think.
I believe it was a multi-pronged setup. I don’t know who were the authors of the dossier information specifically but don’t think guys like Halper and Misfud were part of that aspect. Their job was to create (as Comey called it under oath in Congress) a “mosaic of information” beyond the dossier itself.
The FBI had to know that the dossier itself was garbage. I am convinced the 7th floor was in on it; but they still needed to make it appear as if they were doing things “by the book” as Susan Rice said Obama told them all. Nevertheless, even “by the book” they had good reason not to believe the contents of the dossier. So they knew from the jump they would need more and that is why they put the press on people like Page and Papadopoulos hoping to get something. Then they turned on General Flynn. Then Roger Stone.