I recall we could not log the flight time as it would screw the training stats!
Any time that anyone is in this predicament, log the trip but do not enter the flight time in one of the totalled columns.
This way you have the date, what you did and with whom, where you went - it provides a record for you, but this doesn't "screw the training stats"!
At the age of 66 and no longer flying, I get some enjoyment of sometimes flicking through my logbook and looking at the pics!