Ability to split tag values for "Publisher" and "Grouping" in the tag editor?

[CStallion]

I'd like the ability to split tag values for the "Publisher" and "Grouping" fields in the tag editor.  As an example, I have an original song where a composer created a medley dedicated to multiple movies.  I'd like to be able to list each movie individually in the "Grouping" field and name the individual publishers of those movies in the "Publisher" field.  I'm open to other suggestions if I'm missing a better way to go about this.  Thanks!