Try to keep it to one thread my lad. Makes it easier to keep a track on whats going on.
Multi-threads make the forum look like a snakes wedding.
As for your problem. Their doing what Cichlids do. Hopefully it'll calm down, but we DID warn against going out to replace a fish with another fish.
Sounds like your O has taken some abuse for your old green, you removed him, put in another sev, slightly smaller, slightly brighter, in your O's eyes, its the same type of fish, hell get the same type of problem, so he really has something to prove while he can.
My breeding pair of Sevs hate ALL plecos... Same reason
Tank is rather over stocked too. Your not going to get natural behaviour from these fish in conditions like this.
Craggy