The Movie City of Joy took a minor character from the novel so it could be a vehicle for a Hollywood star, in this case Patrick Swayze. I think World War Z, mentioned elsewhere on this thread, was guilty of the same, but I can’t remember if Brad Pitt’s character is even in the novel.
I don’t know if this is what you mean, but The Hand that Signed the Paper by Helen Demidenko was a controversial winner of Australia’s most prestigious literary prize the Miles Franklin Award. It won best fiction even after Demidenko family memoir of WW2 Ukraine was revealed to have been written by Helen Dale, the daughter of UK immigrants.
Demidenko and Khouri both feature in the Wiki article List of fake memoirs and journals.