Not sure about all operators but where I was until all this kicked off one of the crew had to do a walk round during any turn/transit...I guess they could do the walk round clanging a bell and have a flashing light on their hat to ensure no mixing occurred.
Last time was involved in professional aviating we had or were doing away with a lot of the traditional paper paperwork
and moving more and more towards electronic logs - for example at base the refueler would ping the refuelling carnet up to the operating crews iPads and if all was OK, numbers added up, the re-fueler would never set foot in the aircraft.. however such systems relied on ground staff having the compatible kit and a robust telephone system or other means of connection. That could be a problem even at base so I suspect a diversion to somewhere "offline"the fancy options may not be available and it will be back to paper paperwork.........
Be interesting to see how this works out in practise as the industry gets going again - no doubt (thinking UK operators here ) Red/Amber/Green status will play into the crew's decision making process for
non urgent diversions and maybe operators will come up with protocols for handling unscheduled turns at the Red/Amber stations.