My theory regarding the mansion trashing is
here.
But regarding the Chad blackmail photos, my guess is it's Mel and Sarah. Somehow they know Chad's gonna break up with Sage, when they spot Sage and the mc making out in the backyard in episode, their conversation hints at some things:
Sarah: "This will make it easier when Chad breaks up with her."
Melanie: "I'm gonna go call him."
Sarah: "Easier...but Sage will still be furious."
Melanie: "If things ever go south..."
Melanie: "...you'll have my back, right?"
Sarah: "Don't I always?"
Melanie: "I'll always have yours too."
They are close to Chad, so maybe he told them he planned on breaking up with Sage, but why are they worried about things going south with themselves, and having each other's back. Unless they are involved in the breakup somehow, it doesn't make sense.
My theory is they sent the photos to Chad, blackmailing him to break up with Sage. Not because they are malicious bitches, but because they want Chad and Troy to stop the charade, or at least for Chad to stop using Sage. They were actually trying to help everyone. The photos of Arieth fucking everyone were a smoke screen. They sent all the photos to Chad, and of course he only passed on the Arieth photos to Dawe.
The Cathy cluck, it seems a little too obvious the Alphas were responsible, especially since they were screaming to the highest hills that the DIKs had done it when we know they didn't. It obvious the Jocks are happy to frame the DIKs, but whether the Alphas did it or just took advantage of the situation, I'm not sure.