The heavy crew should ask for the operating captain's wishes.
If one of them is in the way then the operating captain could tactfully ask for a coffee or set some other small task.
I recollect, on takeoff, sitting in the RHS whilst my captain was eating up runway and negating the perf calculation as he tried to diagnose a minor engine problem before setting thrust.
I asked if he wanted to continue or abandon.
The heavy FO immediately said "Don't say 'abandon'."
After we were clean and climbing away I asked him what he meant. His answer was something along the lines of "If you say 'abandon' you'll have a lot of paperwork."
WTF! He had dangerously interfered in a dialogue between the operating crew.
OTOH, on another occasion we had a perceived fuel feed problem in the cruise. Unable to resolve it, the heavy crew were called from their movie and dinner to assist. The heavy FO solved the problem
