For this story, ANH is well established, no doubt about that. For ESB, it was in the original draft, but I’m still working on that bit. As for RotJ, yes that’s sorta rewritten.
In the original draft (where it was only Vader being a clone), it begins with the Bespin duel in ESB, where Vader tells Luke “Obi-Wan killed your father!” The revelation sends Luke on a journey to discover that Vader’s a clone of his father, and Vader did tell the truth of Obi-Wan killing Anakin (seemingly anyway), but it was because of Vader’s machinations. Luke then, goes to Tatooine to build his new lightsaber.
The 2nd part deviated from RotJ, revealing that Anakin survived. It’s further revealed that Anakin originally helped Vader to eliminate the Jedi for the emperor. The emperor has Anakin infiltrate the rebels, who are planning to attack Death Star II, and trying to have Vader killed off. Luke, learning the truth, is startled about his father, but he managed to rescue Vader. The Death Star is damaged, not destroyed, and the emperor’s body is destroyed only for him to transfer into a clone body (remember, this is based off of the Legends EU). The rebels, claiming a major victory with the very emperor defeated, establish themselves as the New Republic, claiming Coruscant at the very end.
Part 3 is five years after RotJ, where Luke is trying to rebuild the Jedi Order while dealing with the reborn Emperor. Vader, imprisoned by the New Republic for info on the Empire’s bases, questions about his loyalty to the Dark Side and slowly turns more grey (and a sort of anti-hero, in that respect). Anakin is still in service to the Empire, is planning to overthrow the emperor and rebuild the Jedi Order in his own image. Teaming with Vader, Luke manages to bring Anakin’s recruits to their side and they stop the emperor from retaking Coruscant. In the final battle, Anakin sees the error of his ways and captures the emperor’s spirit in his dying body. The story ends with Vader going into the Unknown Regions while Luke begins training new Jedi.