What if Leia was at the same level as Luke in her Jedi training at the time of ROTJ? How would things have gone down with Vader and Sidious had both Luke and Leia confronted them together?

Obviously, Leia being a Skywalker would not be a huge secret to Vader at this point.

I imagine the duel with Vader would still be difficult for the twins. I can see Vader relying more on the force (as he did when he toyed with Luke in ESB) to keep the twins separated so that he can take them on individually. It's very possible that he might defeat (unlikely kill) one of the twins (twin #1) and that the fear/grief of the other (twin #2) would lead to that one (twin #2) relying on their anger to defeat Vader (as we saw with Luke at the end of ROTJ).

Sidious would then step in to coerce the successful twin (#2) into killing Vader and twin #1 and thus becoming the new Sith Lord. Twin #2 rejects the Emperor's manipulations and both twins confront Sidious together, but neither expects force lightning and the two quickly grow weak from the barrage of dark force lightning. Vader hears the pleas of his twin children to save them and, just as in ROTJ, grabs Sidious, throws him into the reactor shaft, and becomes a redeemed Anakin. He then dies after announcing to the twins that they have both become true Jedi.

As I wrote this up, I guess I saw that things would more or less go the same way as in the original story, even with Leia's addition.

What are your thoughts? Would Leia's presence and skill as a Jedi (rivaling Luke) make any major difference to the confrontation with the Sith? If so, how would you see it play out?