by Cynthia Ng
So there does exist a document already on this topic, Getting OCLC numbers into your vendor records using MarcEdit but I found the instructions difficult to refer to. I ended up writing my own version with the added instructions on creating a set of MARC records specifically for this purpose. After doing this sort of thing again today, I finally decided to share them.
https://cynng.wordpress.com/2015/01/07/merging-control-numbers-into-records-using-marcedit/