Why didn't they just sign the papers at the airport? *Spoilers*

My take on it was that _she_ was passive-agressively manipulating John into sticking around longer---because she doesn't want the divorce and also because she feels she's in trouble and he's the only one who can help.

Then again, since he's not part of the conspiracy, they may feel they need to get rid of him as well as her, since he's the only non-conspirator who knows her well enough to realize the doubles are impostors. (He can't tell physically; he has to check for the wrist-implant when they're reunited after her kidnapping.)

In reality, his lawyer would have FedExed the papers to her lawyer. But this is a movie.

They said in the film that they needed him so they could get background information that wasn't in any public record so that the replacements would be able to pass as Elaina. Such as the name of the dog.

dude, "why didnt they just...." is a question I asked myself about 30 times during this film. This has more plot holes than just about any film Ive ever seen. Talk about style over substance, and the style didnt even work