It's a fair question, but I would push it further and rewrite from The Force Awakens onward, as I feel the whole sequel trilogy story line is fundamentally flawed. If I had been writing the story therefore, the basic outline / premise would be:
In the years since 'Return of the Jedi', a fledgling New Republic has been established after years spent battling the remnants of the Empire, which has now all-but disappeared. The mopping up was lead by Han and Lando who are both now senior figures in the Republic's hierarchy.
Luke has established the beginnings of a new Jedi Order, starting with Leia, who is now also a Jedi (Luke is doing what Yoda instructed him to and is actually passing on what he knows). The first new Jedi Knights are making their way out into the Galaxy, and it is two of these that will become the main protagonists of the new films.
The film opens with a small, beaten up one-man fighter being pursued and fired on by a hulking, overwhelmingly stronger ship. The fighter has been through hell, and is covered with scorch marks and battle scars. It does its best to evade the hail of fire, but eventually takes several hits and plummets out of control into the atmosphere of a planet, smoke and fire streaming from it. Seemingly satisfied, the hulking ship turns away and jumps into hyperspace.
Wipe to:
The story proper begins with our two new Jedi Knights and R2-D2 (assigned to accompany them on Luke Skywalker's recommendation after a troubling Force vision) being sent to investigate rumours of an unknown fleet massing in the extreme outer rim of the galaxy. As they near their destination, they encounter a planet unexpectedly strong with the Light side of the Force. It is the same planet we saw the fighter crash onto earlier. The Jedi detour to investigate and find Ahsoka Tano living there! She is now a fully grown Togruta, like Jedi Master Shaak Ti. The crash we saw was hers, but it took place 10 years ago. She has been living on the otherwise uninhabited world ever since, unable to escape since as her ship was too badly damaged and the communications array destroyed. Ahsoka had been on her way back to the Republic with terrible news when she was attacked. She too had heard rumours of a fleet of ships massing on the outer rim, but she had made the mistake of investigating it herself before reporting her intentions to the New Republic, so no-one knew where she was or what had happened to her. The news she had uncovered was that the fleet was actually under the command of a new and unknown Sith Lord, who had been biding his time and building a vast new fleet in secret until it was of a size and strength to overwhelm the New Republic's forces. In reality, much of the old Empire's remaining forces had also made their way to him, with only a small number of their ships being sacrificed to battle the New Republic to give the impression of resistance. The Sith Lord has been cloning new troops and his forces are on the brink of being ready to attack and dominate the galaxy.
The two new Jedi and Ahsoka race back to Coruscant to inform the New Republic's leadership of their discoveries, just as Darth Vengeance and his powerful young apprentice, Darth Rend begin their attacks.
Vengeance was a secret apprentice of Darth Vader's, who rose to fill the void after Palpatine's death. As his military forces start their attacks on the New Republic, Darth Rend will be sent by him to strike at the New Republic's heart by destroying the new Jedi Order by targeting the new and inexperienced Jedi Knights, which he starts picking off one by one.
And the story would advance from there. Luke, Leia, Han, Lando, Chewie, C-3PO and R2-D2 will all feature, especially in the first film, but (apart from the droids) will be mostly secondary characters as the torch is passed to the new principles (the two young Jedis and Ahsoka), who see most of the action. I could come up with more plot now, but since it's never going to get made and this isn't meant to be a novel, I will end it here.