I started out with the wiring harness from my donor '69 VW sedan and then added a bunch to it for the other stuff I wanted.
A great deal of hair-pulling ensued.
Very similar process to what Carey's elves are most assuredly using on your harness (but I had the advantage of an official VW wiring diagram that was, at least, accurate for the original stuff).
He/They deserve at least a case of really good suds for their efforts.