So, we all know who the Oceanic Six are:

Jack, Kate, Hurley, Sayid, Aaron and Sun.

We also know that some of them (if not all of them) at...

This is what I think could be the undoing of Ben. Claire didn't want to know Christians name, so I assume that there is nothing registered. I think that maybe when Jack got home he saw his Fathers will and this would have mentioned Claire. Christian died in Australia so I think his solicitor would have read the will as normal.
I just think that maybe Jack now knows that Ben doesn't know everything and maybe he needs to get back is smoething to do with that.

I see..Hmm, i get what you're saying, but Ben can't be one of the Oceanic 6 because he wasn't on the plane.

I see that you're suggesting that Ben is posing as one of the 815'ers? This is possible, but I just don't see it being the case, as we know that he can get off the island if and when he wants - he still has Desmond's boat and could leave on the same bearing as Mike did. I'm thinking that the O6 must return unannounced and then make their survival public (or at least a version of events). We know that Mike returned unannounced with no media buzz or knowledge..which leads me to assume that Ben and the O6 could do the same, which means that Ben wouldn't need to pose as an 815'er since he could just blend into the real world (like it seems he's done in Sayid's 4.03 forward flash)..

If Ben is not one of the O6 (and I don't think he is), then surely this means that Aaron has to be..?

Good point and you're probably right, he probably didn't recognise or even know what Sayid looked like. Your theory could work..but I think the answer is that the man is an employee of Widmore..someone who's expertise helps Widmore's company/offshore connections (assuming Widmore has some sort of control over the island at this stage)..and so by killing him and people like him (Wimore employees), it means that Widmore's control over, or pursuit of, the island is diminished. I think this is why Ben and Sayid are after these people - because it's their way of protecting the island, or of killing Widmore Industries from outside.

I don't think everyone who works for Widmore would know what the O6 look like..but they may know that theoir employee has a connection to what happened to 815 (upon the return of the O6, did the 'staged' wreckage get outed in the real world as being 'staged', and consequently Widmore's name - regardless of whether it was actually him or Ben who was responsible - get dragged through the mud in relation to 815, thus explaining why his employees have only a vague knowledge of who the Oceanic 6 are and what they look like etc?).

Of course, i'm assuming that the man was an employee of Widmore and accept that this explanation might not work otherwise.

Kinda answered this above, but yeah, you would think that he would ensure that his people knew what and who to watch out for...but not necessarily, because this island and his actual plans in relation to the island might not be divulged to these people. Only high ranking officials would perhaps know the full details..people like Mr. Avellino might only know vague connections between his employer and the O6/815.

That said, this will indeed need explaining at some point, and i hope they do come back to this issue. I do think this angle works..it just needs a bit of clarification as to why a seemingly chance encouter turned into what it turned into - that is, why didn't he know WHO Sayid was. There's scope there for a good explanation - hopefully I've offered one, although I expect they'll have a better one.

Yeah, it seemed that Jack was unwilling to hang around with Kate because of Aaron - does he know that Aaron is his nephew? Seems likely..

Perhaps Aaron serves as a reminder to the choice he(?) made, or a reminder to what happened to his step-sister?

Interestingly he doesn't seem to be blaming Kate - he even stood in her defence..which suggests that however Kate got Aaron, it was either Claire's decision, or Claire wasn't around to make the decision.

That said, I agree - I think that at the time of receiving Aaron, Kate knew full well that it would be advantageous to adopt him..

Okay, heres a thought. Not only would Kate have received a large settlement from Oceanic Airlines, but so would Aaron have. Why would the system just let Kate adopt Aaron without first contacting the natural birth father to take custody. I know he did not want the baby at the time, but considering the large sum of money involved you would think he would have wanted to adopt the baby himself.

My guess is that no one really does know Aaron is Claire's baby. The world at large believes that Kate is the real mother of that baby and that Claire died before giving birth.

I don't think that the Oceanic 6 were handpicked by anyone after thinking it over again. I think it just happens by circumstance.

Although i would like for Jack to find out the truth about Claire in a more 'dramatic' manner, it could well happen like this, after all it is logical to assume that Christian left a will.

I would disagree on the issue of Ben - I think that Ben does know pretty much everything about the island (although apparently not what Smokey is) and that Ben's death (if it's him in the coffin) would mean that Jack has less chance of ever getting back. Although I can also see how this could work in the way that you put forward.

Interesting point about the settlement KF - I keep forgetting about that!

Good point re: Thomas..he seemed like the type to be interested in a rich baby. Although on the otherhand, he also seemed like the flakey type..someone who despite the potential riches that Aaron had, wouldn't want to get his hands dirty changing nappies and taking responsibility for his child I guess it could work both ways, but good point nonetheless, as it's important to question whether or not Thomas (Aaron's daddy) is in the flash-forward picture.

However, I still think that the world does know that Aaron is not Kate's, as everyone knew that she wasn't pregnant before getting onboard that flight. It would also make sense, i think, for one of the two people who they said had died after the crash to be Claire - otherwise why even mention that there were 'any' other people who survived this initial crash?

In saying that you point about Thomas does make this far from cut and dry