OK, seems like we're struggling with why the third guy is there, and whether he has to be there. At a minimum, he's there because the contract says so, and I think we want to be in the business of enforcing the contract.

Regardless of the reason, you've got three guys. You want to use the third guy? He needs to be rested, because he's liable. If you want to go the other way, like CAL used to, then let's put the relief in the cabin, with a Scotch in hand, for the outbound leg to Europe.