I have a situation concerning a published parody/retexting of "The wearing of the green". I have a name for the "creator" of the song, the guy who gave it a separate title and identity from "Wearing...". But this creator had nothing to do with the actual composition of the music, only the lyrics. If I were to catalog this for a library, I would give "Arnold, Ripley Allen, 1817-1853, lyricist' as the chief statement of responsibility in the 100 MARC field, with a 730 field for "Wearing...". But IMSLP doesn't really work that way. (To use a concrete example from my childhood, I'd file "Hello muddah, hello fadduh" under Allen Sherman and not Ponchielli).
As I see it, there are 2 ways to do it here.
Composer: Anonymous.
Lyricist: Arnold
or
Composer: Arnold
Lyricist: composer.
I lean toward Solution #2, as IMSLP is organized to have composers as the chief person of responsibility. But I didn't want to create problems for somebody if that wasn't policy.
(The item is OCLC # 44555831, if you want to see it in WorldCat.)