Marvel Chronology Project

I just read Iron Man: Legacy 6-11 which features the Illuminati.
This was discussed during publication here viewtopic.php?f=2&t=5149&hilit=iron+man ... y&start=15

The biggest problem is the Serpent Society and Puff Adder.
As was suggested by oenglish, the formation of the Society in Cap 307-309 are flashbacks.
The Puff Adder in Legacy can be another one from the one introduced in Cap #338 (unless they are time displaced, though I don't like that solution in view of Wilder paying them on Sidewinder's bank account).
As also suggested by oenglish Tony/SHIELD don't know of the Serpent society only of Sidewinder. Tony refers to "Serpent Society" because that's how they call themselves. (And since we remove "Serpent Society" known to SHIELD, we also keep it possible that they are time displaced by The Pride)
Pr X states he was on board Lilandra's starship.

The Captain America Index places this for some of the Serpent Society members, and since we've updated the MCP from the Cap Index this arc of Iron Man Legacy is partially placed in the MCP. Take a look at Puff Adder's and Diamondback's early chronologies, for example.

Of course, we still need to completely add these issues to the MCP, but the larger questions have already been answered by the Index. Is it canon? Where does it occur for the Serpent Society and Puff Adder? etc.

These continuity concerns were raised with editorial when the Index and Captain America handbooks (with Sidewinder entry) were being worked on. The ruling was that it was canon, that the Serpent Society seen was effectively a dry run for the later one Sidewinder formed, and that Puff Adder was there, but didn't make the final cut for the initial Society for some reason. No explanation was proposed by us to editorial or provided by editorial for why Puff Adder felt the need to introduce himself to Sidewinder when they had already met, as we felt we didn't require to fill in all the blanks with official explanations, but if you want an option, we might assume that Sidewinder wiped Puff Adder's memories (and maybe the others) when he dropped him, just like he later did to Princess Python, in order to keep the Society idea a (relative) secret.

And yes, that doesn't solve all the other continuity glitches that arise from IM: Legacy, but it's not the first time a story set in the past doesn't gell neatly, and figuring how to make it fit requires some no-prizes and a bit of gritting our teeth and squinting a little (e.g. ignoring when people are in the wrong costume / assuming the current costume is in the wash and they put on an old one that day).