Workflow - Merging, reconciling and separating out subject terms

In upgrading legacy metadata, I spend a lot of time wrestling with controlled or not-so-very controlled terms:  LCSH terms, local terms, red terms, blue terms, FAST terms, slow terms.

Here's a quick, not-overly-detailed sample workflow for 1) merging multiple columns containing subject terms, 2) reconciling subject terms to LC's vocabularies, and 3) splitting matched (LC) and unmatched (non-LC --> local) subject terms into two separate columns.

This workflow assumes that you have set up reconciliation services.  If you have not, Freeyourmetadata.org has easy-to-follow instructions.  I strongly recommend that you locally host a data dump of whichever vocabulary you are wanting to reconcile against so that 1) the process will run faster, and 2) you aren't taxing someone else's server.