You could call these screen "uncredits." Rewrites that contributed substantially to the produced screenplay, but not enough to garner screen credit.

Curiosity Kills

A 1990 USA Cable movie.
Your basic 'B-movie' thriller, set in the downtown L.A. artists' loft district at the cusp between the '80s and '90s... Starring C. Thomas Howell & Rae Dawn Chong (back when they were still married), Jeff Fahey (as the villain) and a pre-"Friends" Courtney Cox.

Borst/De Palma to the rescue...
We did the production rewrites, focusing on character and dialogue, but the changes weren't sufficient to garner residuals.
This still shows up from time to time on USA Cable...and I believe it's also available on video... There are worse ways to kill time...

Open House

A late-'80s low-budget independent feature from Intercontinental Releasing.
In the grand tradition of Halloween--your basic psycho-killer exploitation pic...
Starring Adrienne Barbeau and Joseph Bottoms.

Did the post-production rewrites. (The movie made absolutely no sense, so De Palma & I were brought in to put some mortar between the bricks. Responsible for about 15 minutes of the movie.)
This still shows up occasionally on USA Cable ... and some of the premium cable channels ... and it might also be on video.
In the right mood, it can be a hoot ... and actually garnered a somewhat favorable review from Variety...