A new verse may be added to a finished song. Usually the change is so small that there’s little reason to make it a new work.
But sometimes the change can be quite big especially when it’s covered by someone else. A well-known example is the new verse “R-E-S-P-E-C-T, find out what it means to me; R-E-S-P-E-C-T, take out TCB” added to the Otis Redding song “respect” by Aretha Franklin. (and most of the covers are actually doing this version)
In this case, should the new version of “respect” be regarded as a new work?
Another question is whether aretha’s recordings should be defined as covers as she is the first one to sing this version.
The additional verse “Poets often use many words to say a simple thing…” (first sung by Nat King Cole) in the jazz standard “Fly Me to the Moon” may be another example.
A less relevant example is the Whitney Houston cover of the Dolly Parton song “I will always love you”. The “I hope life treats you kind” part was simply spoken in the original song, and a new melody was written for the cover.
I have learned that hip hop remixes with new verse can have separate work pages in previous discussions, but still not sure for these cases.