Howdy, Lewis, welcome to the Cove!!!
There are two parts to this requiremnts. 1) OJT for personnel in any new or modified job affecting product quality and 2) appropriate records of education, training, skills and experience.
Now, I would assume that supervisors have jobs that could affect product quality, and you may have actually stated so. this often occurs when an auditor askes how you know the supervisors are competent. The common reply is they were trained on the job (or something like that).
Now, the very next question from the auditor is; "Where are the records?" A very logical question. Your answer must be equally logical. If you say; "We don't have any." Then why not?
The real question here is are supervisor OJT records "appropriate"? What purpose do they serve, and why should we have them. I for one, and not totally convinced they are appropriate. I also think a list of "grandfathered" employees is not necessarily appropriate. If we keep a record just for the sake of meeting a regiatrar's request, the record is not appropriate (IMO). There are others who will undoubtedly dissagree.
Typically, that is the way I would present it to the auditor. Let us know how this turns out, and why the auditor thinks they are appropriate.