As Independent Instructors, when we do DMs we ensure that they have complete & current copies of all their paperwork so that if the occasion arises for them to train with another Instructor, they can "plug in" to that activity & have that section signed off by that Instructor. We then ensure that we meet with the DM on an ongoing basis to compare & update the paperwork to reflect any changes.
That way the DMC has the opportunity to train with other Instructors as well as get their training done more expediently.
Interesting.
As the instructor who's name might ultimately end up on the back of the DM's card (ie: you are "certifying" that they are DM caliber) do you have any concerns about - or mechanisms to determine - the quality of the "sign off" by another instructor? Some other instructor's "4" rating might be a "2" in your book. Do you need to know/approve of any other instructor before allowing them to sign off on your DMC?
At the shop where I did my DM training we would work with many different staff instructors, but they are all known entities, adhering to the same, high-level of standards in evaluating DMC's, so not a problem. I'm just wondering if/how you exercise QC over a process you are not necessarily involved in.