At the end of Being John Malkovich Craig becomes trapped inside Emily. Lester, and his friends, plan on using Emily as their next vessel. Since Craig is already there, is it impossible for Lester to use Emily? Or, because Craig is unable to control Emily, can Lester still do it?
According to Lesters explanation in his library.
Craig is absorbed into Emily because he tried to enter the portal after midnight on Malkovichs 44th birthday.
Lester & Co. however will enter Emilys mind on HER 44th birthday and still have full control
Just for cannon reference: Vessel Scientific Explanation