Flaw in the plan

There are a lot of things that could have unraveled the plan considering how complex it is (after all, the more complex, the more something can go wrong, right?). You're bringing up probably the most egregious potential 'flaw' in the plan, which is completely plausible, but throughout the movie you can see how nervous and reluctant Roy is even to contact/phone his ex-wife and say 'hi', let alone discuss their daughter.

I think once he asked Dr. Klein to call his wife FOR him was the moment it became clear that he didn't have the wherewithal to speak to her to any degree. Towards the end of the movie when Roy tells Angela he'd contacted his lawyer who specializes in child custody, he even tells her than he hadn't even informed his ex-wife of his intention to fight for joint custody. That's some SERIOUS ex-wife fear if you ask me, hahaha.

And also, considering that Roy and Frank had been partners for so long, Frank would likely have known that Roy was really hesitant when it came to contacting his ex-wife, so that was one variable in the plan that I think he was content with, or at least willing to leave as a variable.

he didn't talk to her for 14 yrs, and the shrink told him she doesn't wanna speak to him.

i mostly will not be able to answer your reply, since marissa mayer hacked my email, no notification

If Roy had not flushed down his meds by mistake in the beginning we would have no con. If he had found his own doc instead of letting Frank call his... this is the biggest imo. Can be explained if Frank just had the whole plan on backup in the odd case Roy may loose his meds and not get a new doc to assist. Not impossible, but highly unlikely.

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