I don' t think there is anything to compel Marcone or Namshiel to follow orders from Nic, nor do I think Nic would even bother trying. My sense is that the Denarians that follow Nic do so because their Fallen have a similar mind to what Anduriel wants to accomplish. From what we've seen of Namshiel, he has a different agenda. Plus Marcone seems to have a similar obstinacy as Harry when it comes to letting someone bend him to it's will. We're assuming Nic knows about Marcone because we're making the assumption that Nic/Anduriel for lack of a better word stalks the shadows of those he's interested in (Marcone would qualify for that, even before he took Nic down a few pegs). I don't believe we know for certain that the Fallen have some sort of way of knowing when coins are taken up...it seems like generally Nic steals the coin, plants it on his intended target, then waits for the Fallen to come to him.