Don't forget that the SA-CAA do not have a rating such as co-pilot only. They have only 3 ratings...P1 (pilot-in command), PI (pilot-instructor) and P1 Restricted ( what the relief pilots get).
So if you are flying a multi-crew aircraft, the operator should specify who is the PIC for the flight, and the other pilot should log P2 time.
Of course, who is likely to check with your previous employers as to which legs you were P1 or P2.
Of course, the cadet pilots will have a bit more of a problem, as records of all their flying is recorded.