In regards to the prologue:
Proposed name is "Waiting (Vortex)" or "Prologue - Waiting (Vortex)"
In regards to Convergence, Part 2:
The team will land a bit further of where Eris and Kin are, so they will not immediately know that they are not alone there.
Eris will drag Kin closer as she spies on the team, trying to figure out who she's dealing with (cause she doesn't know yet that she's the one who got them there, so she suspects them for possibly being energybenders themselves).
The overhears the team bicker and observes them, getting to know some details about the characters that could otherwise not naturally be transferred to the reader.
Ex: she could read Yuhan's energies and deduce that he's an earthbender with an internal struggle between duty and feelings (something only SHiE readers would otherwise know).
In regards to Chapter 5:
The team will find the vortex inside Wan Shi Tong's Library, but figures that they might as well take advantage of the library's knowledge to find out some information about what's going on. To that regard the team spreads out, agreeing to meet back at the vortex at a set time.
At that same moment, Eris is also at WST's Library, albeit in her own world. There, she has figured out that the vortexes and the team are connected. She senses the team's energy in the library and creates a vortex of her own to travel to the Slash-verse.
The four guys are waiting at the vortex for Ursa, but it is Eris that arrives instead. They get into a fight, which Eris is rather easily winning. (Girl power FTW!!) At the moment she's severely hurting Yun (strangling him or whatever), Ursa returns. She screams in distress over Yun's situation, and rushes to his aid. She crashes into Eris or whatever, and the two girls fall through the vortex.
This will be the only indication that Ursa has a thing for Yun. Any other mentions of her crush will be taken out.
As the vortex is shrinking, the boys get up and jump through after their friend, but the few seconds in between are enough for them to land elsewhere in the Air-verse than Eris and Ursa did.
In regards to Chapter 6:
Yuhan and Ling will know why Ursa did what she did, having loved ones themselves. Yun is still oblivious to Ursa's crush. Kaddo will catch on as well, though the other two want to keep that information on the down low, not wanting to embarrass Ursa and/or Yun.
The boys meet Ursa's older self.
Ursa and Eris land and immediately start fighting each other. Ursa is rather aggressive due to her romantic feelings for Yun and the fact that Eris nearly killed her love.
Eris will not be able to energybend, since she is in a different world, and as such, she has to adapt to the foreign energy. During the fight with Ursa, she is forced to firebend in order to save herself.
Perhaps Ursa could singe Eris's hair. That would piss her off enough for her to resort to firebending, even though she vowed never to produce a flame again.
The reason why Eris could bend in WST's Library is because that is a very spiritual place, and the spirit world seems to be the only thing that is the same in every of the involved universes.
Ursa is the better firebender since Eris hasn't practiced in ages, and captures her. The two thus travel the Air-verse together in search for the others.
Ursa has learned that Eris used to be a firebender. Eris might possibly let slip that she hates the ability cause it's the same native element as her father.
Eris will tease Ursa about her crush on Yun.
Before the team meets up again, Eris has adapted to the foreign energy and breaks free. She vortexes out of there.
The team finds their vortex and are transported to Eris's past.
In regards to Chapter 7:
The team will encounter Kin and Sakura. They all recognize Kin, and Ursa sees Sakura, Kin's only daughter, firebend, thus putting two and two together about who she is -or rather, will become.
The Team does not say anything to Kin, cause that will just create a paradox and a whole lot of trouble that will give us a headache if we have to explain all that :-p
There will likely no longer be a separation chapter, as we can't really place that in the current timeline.
The Vortex story basically has two parts: 1. the team figures out what's going on and all by traveling to the different worlds. They also discover that they are in a loop. This part ends with their realization that they'd need Eris's help to stop it all. And 2. they try to mend the bond between Eris and her father, cause Kin's energy is needed as well.
That's about it, I believe. Any comments and/or additions, fire away.