[KHS]

Until now I don't maintain composer and lyricist in MSP.
But if I would, I would put all in MSP's "Composers" field separated by | and specify with a prefix or postfix if it is composer or lyricist.
Thus "Custom Groups" stays available for other use cases.
Additionally: often just a list of names is specified on a score without mentioning who is composer and who is lyricist.

Example
on a score of "I Can't Give You Anything But Love" I find "J. McHugh & D. Fields"
I can look up e.g. in Wikipedia "by Jimmy McHugh (music) and Dorothy Fields (lyrics)"
I would store it in the "Composers" column of CSVs as "McHugh, Jimmy (music)|Fields, Dorothy (lyrics)"
MSP creates on CSV import two database entries in "Composers", one for "McHugh, Jimmy (music)" and one for "Fields, Dorothy (lyrics)" that are displayed as shown by attached screenshots

Thanks, Mike and Herbert. All good suggestions, but I like a separate field for lyricists consist with the construction of my pre-MSP sheet music database and to make it simpler to search only one or the other. Agree that it requires add'l research or knowledge to know who's who.

I would like to be able to do standard Windows right-click copy of an entire entry. I do like that they become committed and thereby more easily re-used and reliably searched upon. Maybe it could turn into text if I pasted it in a text-only field (like Keywords)? 

Either way, I renew my request that when I rename "Custom Group" to "Lyricists" that CSV imports attempting to fill the Lyricists field would be honored rather than having to import a fieldname "Custom Groups" that no longer displays anywhere and is not intuitive. I'm still confused why it appears as "Custom Group" but to fill it on .CSV import, I have to call it "Custom Groups" [plural].