coscript

From co- +‎ script.

coscript (third-person singular simple present coscripts, present participle coscripting, simple past and past participle coscripted)

1. To write (a script) together with someone
   • 2009 September 12, Peter Howell, “Clooney at his funny best finds first-class isn't tops”, in Toronto Star‎:

     But Reitman, who also coscripted the film (with Sheldon Turner) from a novel by Walter Kirn, isn't interested in merely satirizing the existence of guys like Bingham.