This would only be possible if the cars had some special equipment. General service cars were free runners and stenciling really meant nothing.
You could get around this by classifying a car "XP" but this did not help that much until the advent of CSD 155 which is close to 20 years beyond this group's time frame.
I have seen painting diagrams that specify that any assignment stenciling is supposed to be re-applied to the painted car. There is no mention at all of a method of determining whether the information is correct of if there is even a Shipper at that point that is loading any cars. Those kinds of painting instructions just sort of died out.
Russ > Someplace that shipped flour is going to want an A class boxcar and if the town it's in doesn't receive all that many boxcar loads the local road might choose to label some cars "when empty return to..."
Such lableing was no assurance of having the cars returned. It did not supplant Car Service rules. Most railroads, other than the one doing the stenciling, would hjust ignore the stencil.