BTW, who is commanding the plane (by inputs) and who is commanding the crew are entirely separate questions. I think one of the serious issues that MUST be addressed here is the issue of conflicting commands to the plane.

Two options.... 1) Place all controls between the pilots so they can easily see what eachother is doing or 2) Place a selection switch and indicator that allows a pilot to unambiguously take control of the plane and disable the other input, or to keep them in linked mode where they move together and provide tactile feedback as to what the other input is doing.