Retroactive Continuity

Retroactive continuity or simply a retcon, is a literary device in which an established storyline is adjusted, ignored or contradicted by a subsequent work. There are small examples of this in the Scream film franchise, despite its single continuity narrative, in contrast to the Halloween franchise.

Background
The first known attempted retcon of the franchise was considering reviving the character of Randy Meeks in Scream 3 following fan backlash of his death in Scream 2. It was decided against. Instead, he appears in a video tape, in which he actually refers to the concept of a retcon, common in trilogies.

The second known attempted retcon was strong considerations of reviving Stu Macher as the villain of an early treatment of Scream 3. Actor Matthew Lillard stated this was to actually happen, but the Columbine Massacre scrapped the original idea.

Rules of a trilogy
Randy describes the meta trilogy device of going back to the beginning of a film and rewriting a plot point believed or previously established and twisting it. In this case, the character of Roman Bridger's influence on Billy Loomis killing Maureen is a self-aware retcon.

Sidney in Stab sequels
A notable retcon is the apparent presence of Stab character, Sidney Prescott in the Stab sequels after Stab 3. It was originally implied by Jenny Randall Sidney did not appear again, as she sued them for 'using her story', hence they became fictional sequels no longer "about her" (and a deleted scene with Kirby Reed confirms as such).

However the motivation of fifth film killers Richie Kirsch and Amber Freeman is the disappointment of Stab 8, simply titled Stab (2021), the sequel to Stab 7 (2010) where Sidney's character was absent, seemingly for the first time among other issues.

This retcon establishes the post-original trilogy Stab sequels were not about Sidney, but she still appeared in them somehow. Though it leaves the viewer to question why Sidney threatened to sue Sunrise Studios, hence her motivation for this threat is also retconned. It is possible Sidney won the rights to the story of the original 1996 Woodsboro Murders in entertainment media form, to adapt it for her self-help book in the process of being written. This would go along with Rebecca Walters' comment that she did not read Out of Darkness (2011) because she thought she'd "wait for the movie".

Expanding continuity =/ retcon
However, the Scream films also expand continuity, which is different from a retcon. This is the case for adding previously unmentioned family members or ideas of their origin.


 * Roman Bridger being Sidney's half-brother is not a retcon, as Maureen's past was relatively unknown and she was known to have many secret relationships. (His role as the mastermind of the original trilogy, however is).
 * Martha Meeks is Randy's previously unmentioned sister. The first two films ignore Randy's home life, so it is very possible he was not an only child or an orphan (parents unmentioned as well).
 * Judy Hicks is a mother in her second appearance. Her role as a mother is unmentioned, but given she was a secondary character, it was not important to address.
 * Stu Macher has a younger sister who had a son. This was hinted at with props in the original film.