In this situation I assume that the Pilot resting would have to be woken up and return to the flightdeck if one of the other 2 members HAD to have a toilet break.
Why? With two crew ops one pilot goes for a comfort break and a cabin crew memebr enters the flight deck.
In the US at least, there has to be at least one pilot with at least "enroute" PIC qualifications. IOW, you can't just leave 2 FO's up front, one has to have more than FO qualifications.
Okay I am not familiar with US rules, or is this a company rule? Surely there can only be one PIC or are you saying the baton is passed when one goes for rest? Can you point to a document I can read? The majority of the rest of the world is not like this
AFAIK. Happy to be shown otherwise.