A composer/writer/co-writer box would make a lot of sense, even for 40's-50's collaborations like:

Rodgers/Hammerstein
Rodgers/Hart
George Gershwin/Ira Gershwin
Lerner/Loewe
Cahn/Van Heusen
Green/Comden

or even TV/movie theme/soundtrack composers like:

Allyn Ferguson/Jack Elliott
Alan Bergman/Marilyn Bergman
Tim Rice/Elton John

and beisdes Carole King & Gerry Goffin, you forgot the famous

Ellie Greenwich/Barry Mann
Burt Bacharach/Hal David
Barry Mann/Cynthia Weil
Burt Bacharach/Carole Bayer Sager
Tom Kelly/Billy Steinberg
Dennis Lambert/Brian Potter
Tom Snow/Dean Pitchford
Jimmy Jam/Terry Lewis
L.A. Reid/Babyface

Just those alone would constitute a great majority in many people's collections.

I like the idea of a writing credit box. On every website, most times a writing credit is given, and sometimes, it would be nice to have the option of searching everything you have by that particular composer, classical, pop, rock, jazz, whatever. Especially on singles and 45's. It would be nice to have a drop down box for the above names, because I probably have hundreds of singles for each collaborator noted above. Think of all the cover versions, too! Some were so prolific, that it would be nice to not have to type in the composer info each time. I could just click on Goffin/King, for instance, and do a hundred singles for just Goffin/King. I can see where it would work great for singles. Some albums have so many composers on them, though, but maybe a box in the "Track Properties" for each song. If all the songs were written by the same person/people, it would be nice to be able to have an option where all songs for that particular album would simultaneously have the same composer credits added. Otherwise, copy and paste.

You are on the right track, Joebugs. I wholeheartedly agree with you. It's a thought Andrei might want to consider in some form or another.