Maybe it's telling us that the timings are indeed very awry (I never did sort out when Ollie was born)?
I have another theory brewing up as I rewatch ep4.
What Tony signs in Ian's office has 'contract" in bold. What is he signing?
How far did investigators go into Ian's affairs following his disappearance? What was this contract? Was it something designed to be Ian's 'insurance policy'? - something that would stop Tony speaking up if he discovered something damning about Ian (which might not be connected to Ollie's disappearance, but might be surfaced if a clean and extensive investigation took place in Chalons).
Did Baptiste see it in 2006?
What was in the second envelope?
Who, apart from Vincent (who I have pegged as interpreter for criminal activities), worked for Ian? Would Mary have come over in aftermath of Ian's disappearance? Could she have access to personal papers, and is what she discovered (maybe in a private safe) what led to her locked-in state?
How did Emily know where to find Mary?