Can Surkov and Trubnikov still fog a mirror? If those guys that Steele claimed were his sources' sources, since Steele didn't talk to them directly, are still alive, then they are the only Russians involved and fed Steele disinformation.
But I am going to quibble a bit here. Although Mifsud ran in the same circles with FBI people, his interactions were more with intelligence agencies at the higher levels. I would think Italian intelligence brought him in as a favor to Brennan, not Comey.
Brennan was in direct contact with GCHQ (Brit intel) headed by Hannigan who promptly resigned after the election. Halper, who was on DOD's payroll, was on the other end of the push pull operation in London.
Unsure if Haspel, who was Station Chief there, was fully in the loop or not. Appears to me this operation was done by those at the top of the food chain of the intelligence community.
The reason the FBI was brought in has more to do with Fusion, GPS peddling the Steele dossier to them and the State Department.