Buona Sera, Mrs. Campbell was twice made into a musical.
The first version,
Carmelina was a huge flop, despite a number of fine original songs by Alan Jay Lerner and Burton Lane.
Like every respectable respecter of copyright, they purchased the rights to use the story, and the original was credited on the poster, playbill, album, etc.
What can I say about the second version? It didn't use any original songs. Rather, it took a bunch of old pop hits from the disco era and told the same story in witless and lugubrious fashion. Worse still, it doesn't credit
Buona Sera, Mrs. Campbell at all; the author claims the story to be original. If I'd adapted something so offensive and smarmy, I'd deflect credit away from myself. And that's not a knock on
Buona Sera, Mrs. Campbell, it's just how the second musical version feels to me.
Of course this musical that stole everything is a huge hit, and its film version became the top-grossing movie musical in the history of British cinema,
Mamma Mia.

Happiest of birthdays, TCB