If it were up to me, I would've scrapped this movie entirely or Spyglass actually apologizes to Melissa and we get a best of both worlds, with the Carpenter Sisters and Sidney's family. But since that didn't happen, I'm going to try and make chicken salad out of chickenshit.
The killers would've been Hannah and Lucas as was suggested originally, with a hidden mastermind orchestrating everything who doesn't get caught.
See, the problem with the Ghostfaces we actually got is AI slop and...well
The other problem with Scream 7, is it played it too safe and it became the kind of movie that Scream itself would make fun of, Scream became Stab.
So this would be my Ghostfaces. Also yes, no fucking AI Kevin, you fucking troglodyte
Lucas' motive:He is someone obsessed with Woodsboro killings, so I'd make it a true crime styled motive, basically what they tried to do with Greg and Jason
Hannah's motive. Hannah is related to Casey Becker. After Casey's death, Mr and Mrs Becker had another daughter and that daughter had Hannah. Hannah's lived in a bitter shadow. Her mother was sheltered, but Hannah discovered the truth and when she learned what happened to Casey, she believes Casey was robbed and what should've been the rightful final girl and wants revenge on Gale for profiting off of her aunt's death. Given she is a drama student performing in a play in the film, her motive could be that she views the killings as the ultimate performance art
The unsuspected mastermind:Tatum. Her motive is she was in the shadow of her mother and helicopter parented her entire life and the only way she can break free is killing Sidney. Sidney ruined a lot of opportunities for Tatum. Boyfriends, Private schools, job opportunities and colleges. She's felt imprisoned her entire life and now she wants to become her mother's trauma to free her shackles and her sisters before Sidney can ruin their lives.
They would use smokescreen killers. Hannah being rich, she would pay off heavies to be the killers to make the kills look convincing and when the time is right, then they strike.
Sidney, Gale and Mark(this timeline, he's actually Mark Kincaid, dipshits) would all have qualms about killing kids, but would do what it took to protect their daughter.
Lucas and Hannah eventually dies in the end.
Tatum is never caught or even suspected by the main cast, but rather she survives Scream 7 unscathed, pulling a Keyser Söze or in this universe's case, pulling a Doofy.
Scream 8 is then told from her killer POV, including the planning, recruiting sidekicks from the Woodsboro subreddit, avoiding the cops, fooling her parents, the chases, just everything and the ultimate reveal that she was behind everything. Tatum's accomplices are killed and before Sidney can kill Tatum, she gives her a pleading look "Mom...please" Sidney can't do it.
Sidney can't bring herself to kill her own daughter. Sidney showing a moment of weakness or mercy, she forgets the headshot rule and it costs her someone close.
Gale goes "Sid, did you take the shot"
For a moment, she hesitates to answer.
"Tell me you too-
*gunshots*
"No auntie Gale, she didn't"
Gale drops to the floor and before Sidney or Mark can do anything, Tatum leaves and Tatum is out there and can strike at any moment.
However if Spyglass finally does apologize and make everything right to Melissa and Jenna, then we can have Christina come in as Tatum's sponsor and mentor and that's reason enough for Sam and Tara to come out and help in 9.
Scream 9
Tatum, Christina and Leslie Macher against Sidney, Mark and the Core Four.
Opening kills:Martha Meeks Martin and Danny Brackett.
Funerals for Gale, Martha and Danny. Everyone is united with the common cause of ending this nightmare once and for all.
We know what everyone's motives are.
Christina. Wants revenge for Billy and against Sam for ruining her life and turning Tara against her
Leslie. Her brother and son was killed, she blames Sidney for Stu and Sam for Vince.
Meanwhile Tatum is having regrets. She's showing signs of being indoctrinated by Christina and her friends died for nothing. So there would be a redemption arc and Tatum would help Sidney, Sam and Tara kill Christina and Leslie and end the Woodsboro Cult.