//Also, some timeline things for him if he was a canon character!! Even though he would be briefly mentioned in 1 and 2 (maybe shown as a background in 1 during some school scenes, even) his first named appearance wouldn't be until 3 when he joins Martha to deliver the tape to Stab 3 set. Unlike Martha, though, he'd stick around for the rest of the movie's events to help get vengeance for his beloved older brother.
He would also have a part in the events of 4, as it would be the first time he is a direct target of Ghostface (obviously not a main target, but one of Jill and Charlie's "we should probably get that guy too"). He had moved back to Woodsboro after finding out Martha had fallen pregnant, wanting to be there for his sister and her children (I was also planning for him to have his own children by this point as well, but he doesn't have an established ship yet).
Scream 5 would be the first movie where he is an actually planned-out target, due to his closeness to the first Ghostface attacks and the fact he would be an obstacle for Amber and Richie to tackle before they could get to the Meeks-Martin twins.
He would definitely be mentioned in 6, but I haven't decided if he would run out to New York after news of the first (legitimate, not the copycat) attack of the new Ghostface spree.