I havent read any of your Knights of Ren scenarios because I feel like at least one of you knows a lot more than he's letting on here, and I don't want to "really" know what happens.
Here's what I thought up in my small brain.
1) Luke opens a Jedi Academy , has 10-20 students including Leia & Han's kids or twins - Rey and whoever Kylo was originally, and wouldn't it be great if they had named him Anakin?
2) Rey and Kylo emerge as the best 2 students, even though Luke is a bit worried about Kylo's interest in the story of Anakin/Vader too much.
3) Luke has managed to retrieve his lightsaber from Bespin, and decides to award it to the top student, the most promising one ... Rey.
4) Furious with that choice, Kylo leaves the Academy, and disappears, starts getting more into the Dark Side, and is eventually found bt=y or finds the Knights of Ren
5) Meanwhile Luke is called to help the Resistance vs. the First Order at the Battle of Jakku. He takes his most promising student - Rey - with him, the rest of the students stay behind at the Academy.
6) Luke & Rey help defeat the FO at Jakku, but they get separated or something of that sort.
7) Knowing Luke & Rey aren't there, Kylo leads the KoR to the Jedi Academy and slaughters the rest of the students.
8) When Luke returns, everybody is dead and Kylo is gone. Luke blames himself for their deaths, believes he has failed as a teacher, and goes into self-imposed exile.
9) Rey, perhaps finding out what has happened in a similar manner, stays on Jakku and becomes somewhat like Obi-Wan - a hermit. Eventually she begins exploring the Star Destroyer and finds her old lightsaber there.
10) In the events of the TFA, seeing as how Kylo's toy says "is it true, you're just a scavenger?" That could be brother mocking sister on the life she has chosen after being a prominent Jedi candidate.
That's all I got.