Ghost-write

In his late seventies, Barclay was already an accomplished writer and published author when Truman Voigt contracted with him to ghost-write his first book.

Source: wiktionary

Although the book's content would be Carole's, Brand hired Edwin Seaver to help ghost-write the project. Seaver was a well-known writer and editor prominent in New York literary circles.

Source: wiktionary

I have met authors who ghost-write for golfers, doctor scripts, produce advertising copy, do panel TV shows. . . . These activities can help your books, they can be fun, they can earn money, they can encourage people to gie you free vegetables, or suits.

Source: wiktionary

In flashback, we see Dumont hire Verin to ghost-write some pacifistic essays for publication.

Source: wiktionary