Not quite the same thing, but producer Sam Gesser was obsessed with mounting a musical of Mordecai Richler's The Apprenticeship of Duddy Kravitz. Initially he had Richler write the book and (here's they are again!) Leiber and Stoller write the score, with Lonny Price in the lead, and it would start with a Canadian tour given the source material. But apparently the mix of score and book didn't work--nothing worked except Lonny--and it died in 1984 before even getting to Montreal, where it's set.
He then hired Alan Menken and David Spencer to write a new score, and ultimately Austin Pendleton would adapt Richler's book and direct. Lonny was back but it had a ton of issues out of town (including producers wanting a new happier ending) and never made it to Broadway, closing in 1987 in Philadelphia.
Over the years Menken and Spencer sporadically worked on trying to revise the piece and finally in 2015, with a new book by Spencer himself, and a score that they claim was 3/4 new (I've never sat down to compare it directly with the 1980s demos) but Pendleton was back as director (Gesser had passed away in the meantime) where it played to great reviews in Montreal. And although I don't think it's had any real regional life since (which is a shame) we did get a great cast album out of it.
And ALSO not the same thing, but famously there's the case of Wonderful Town. George Abbott was so frustrated with the score he had, lyrics by Arnold Horwitt and music by Leroy Anderson (who would write the score for the later flop Goldilocks) that with a month before rehearsals had to start, he called up his On the Town collaborators, Bernstein, Comden and Green, and asked if they could help out. They wrote the bulk of the score in three weeks and the rest in out of town tryouts.