The prequels as they were described in the original Star Wars trilogy

It is worth remembering that the Star Wars movies never had a strong connection to the past and a result of that is that you can see the original trilogy already contradicting itself when it was produced, no need to look to the prequels to find a new Star Wars movie that ignores what was established in the old Star Wars movie(s).

That said, the purpose of this post is not to point out contradictions within the original trilogy.  It is instead to say what the original trilogy said about what came before it.  We have the prequels which flat out ignored what the original trilogy said, but what does the original trilogy actually say?  This post is to give an answer to that.

I'm using the theatrical versions of the original films here, as released on the no longer in print DVDs that had the theatrical cuts as bonus disks.  (Though out of print you can still get them, either as a set or individually: first, Empire, Jedi.)

--
----
--

Yoda trained Obi-Wan.

Anakin, Beru, and Owen all knew each other.  Their relationship is never stated but if Beru and Owen are really Luke's aunt and uncle my best guess is that one of them is Anakin's sibling since they talk about Anakin but not [nameless mother].  They know Anakin well enough that they can talk to each other about his personality without ever describing it and have the conversation be perfectly sensible because each knows what the other means.

It is implied that they grew up on Tatooine (Obi-Wan says that Owen thought Anakin should have stayed here, "here" being Tatooine, and not gotten involved.  On the other hand: Jedi Truth.)

Regardless, the Clone Wars happened and that broke up the Anakin-Beru-Owen trifecta because Obi-Wan came by and Anakin followed Obi-Wan off to get involved.

At this point in time Anakin was already a great pilot and Obi-Wan was amazed at how strongly he was connected to the force.  Obi-Wan took it upon himself to train Anakin, thinking he could train Anakin as well as Yoda would have.  (This will mater later.)

Anyway, the "damned fool idealistic crusade" (Obi-Wan describing Owen's point of view) Anakin followed Obi Wan on was probably the Clone Wars since they both fought in them.  (Obi-Wan was a general who served under Leia's non-Vader father, Anakin's role isn't elaborated on much.)  Given that the dark times started with the Empire, and before the dark times peace and justice had to be guarded rather than perpetually restored, it's a fair bet that the almost undescribed Clone Wars represent the Empire's rise to power.

One thing we can say about them is that they were multiple.  It's not, "the Clone War," but instead, "the Clone Wars."

Another thing we can say is that at some point Anakin went from being a great pilot to the single greatest pilot.

Fighting against the growing power of the Empire, which is, again, probably synonymous with fighting during the Clone Wars, Obi-Wan knew that if Anakin had any children they would be a threat to the Emperor.  So when [nameless mother] gets pregnant she goes into hiding, Anakin doesn't know where.  This happens early enough in the pregnancy that neither Obi-Wan nor Anakin realize there are twins involved.

Anakin leaves his lightsaber to be given to his yet to be born kid(s).  (Presumably he makes a new lightsaber to replace the one he left.)  The fact that Leia ended up with someone Obi-Wan served under as her adopted father implies that [nameless mother] went into hiding on Alderaan with the help of Obi-Wan's friend and ally.

Anakin falls to the dark side and helps the Emperor to hunt down and exterminate the Jedi. (This is implied to be a process, not as simple as going into the temple and killing a bunch of kids.)

Obi blames himself for this. Specifically he blames thinking he could train Anakin as well as Yoda, with the strong implication that he'd never taken on a student before.  In his mind, if he'd had Yoda do the training of Anakin things would have turned out better.  This is presumably also when Luke's father starts to become two people in Obi-Wan's mind.  The good man is Anakin Skywalker, the bad one is Darth Vader.  (His "certain point of view" had to start somewhere.)

The good side loses. Obi-Wan and Yoda go into hiding as the last of the Jedi.  I place this event here because Obi-Wan says he hasn't used the name "Obi-Wan" since before Luke was born.  I figure giving up his first name was a part of going into hiding.

There is, it should be noted, no evidence that either Obi-Wan or Yoda knew the other had survived.  Obi-Wan doesn't demonstrate knowledge of Yoda's continued existence until after he is dead which, I gather, gives a Jedi a better understanding of things.  Yoda and the dead Obi-Wan are already in contact before Yoda appears on screen.

The twins are born to [nameless mother] they're separated for further safety.  Luke is brought to Owen and Beru, who knew his father.  Leia stays with her mother.  This is done without Obi-Wan realizing there were twins (Yoda has to explain it to him, which then leaves him to explain it to Luke.)

Regardless of whether or not Owen and Beru have blood ties to Luke, they definitely knew his father, rather well no less, so this divide seems to be giving the male baby to those who knew the father, keeping the female baby with the mother.

I definitely think bringing Luke to stay with people who were, at best, childhood friends of Anakin, and at worst a sibling of Anakin and sibling's spouse, would have worked better if two things were true:
1 Tatooine was not their original home
2 Anakin didn't know they were on Tatooine

The reason is that if Vader obviously knew who they were given how they're able to speak casually and knowledgeably about him pre-name change.  If he knew where they were it makes a certain amount of sense for him to check in on them at some point, especially if one of them is really his sibling.  The result of that looking in would be, "Hey, I have a son!  Totally taking custody."

Bonus points if Owen is so bitter about Anakin's decision to get involved because Beru and Owen were forced to relocate in hiding to Tatooine as a result of being sibling and inlaw of Anakin.

Unfortunately, that's not the story the original trilogy tells.  The only indication of where they're originally from is when Obi-Wan says "here" is the place Owen thought Anakin should have stayed.  He says it on Tatooine, thus the implication is Tatooine is where the three originated.

Anyway, Obi-Wan relocates with Luke to Tatooine, bringing Anakin's lightsaber with him.  He does this without realizing that there were two children.  Yoda, on the other hand, does know.  Minor speculation would be that Obi-Wan brought [nameless mother] to his colleague on Alderaan for hiding and also called in Yoda for extra help.  Yoda was there when it was realized the pregnancy was twins and advised that the twins be separated for further safety. Thus Obi-Wan was given Luke to bring to Beru and Owen without ever being told there was another child.

Putting things in order for the story of Leia is difficult, if not impossible.  Here's what we know:
1 [nameless mother] lived long enough for Leia to gain some memories of her but not many.
2 At some point Leia becomes a part of the royal family.
3 At some point Leia has another mother (Luke has to explain which mother he's talking about when he asks Leia about her mother.)

There are six orders you can put those three events in (and that assumes none happen concurrently) and none of them would contradict what is shown on screen.

So, for example:

1. [nameless mother] dies after living long enough to have memories of her stay with Leia, Leia is then adopted by Obi-Wan's colleague from the Clone Wars, who becomes her not-Vader father and imparts on her the title of princess.  If not-Vader father already has a wife this is when she gets the not-biological mother.  If not then at some point down the road he marries a woman.
2. [nameless mother] dies after living long enough to have memories of her stay with Leia, Leia is then adopted by not-biological mother.  Not-biological mother marries not-Vader father adopting Leia into the royal family as a result.
3. [nameless mother] either thinking Anakin dead, knowing he turned to the dark side, or just not being big on monogamy, starts dating the non-Vader father of Leia.  They marry, thus adopting Leia in the process.  [nameless  mother] dies.  Not-Vader father remarries, thus giving Leia not-biological mother.
4. [nameless mother] either thinking Anakin dead, knowing he turned to the dark side, or just not being big on monogamy, starts dating the non-Vader father of Leia.  They marry, thus adopting Leia in the process.  Either the king/prince already has another wife, or marries one while still married to [nameless mother] (why should Alderaan care about monogamy?)  Thus Leia gains not-biological mother.  Then [nameless mother dies.]
5. [nameless mother] for reasons mentioned above (was getting too wordy), starts dating again.  Specifically not-biological mother.  Thus Leia has to mommies.  Then Leia's mother dies.  Not-biological mother remarries into the royal family, thus adopting Leia into it in the process.
6. [nameless mother] for reasons mentioned above, starts dating and ends up with not-biological mother.  The two of them marry into a polyamorous relationship with Leia's not-Vader father.  [nameless mother] dies at some point after that.
7. There are also possibilities that involve [nameless mother] giving Leia up for adoption which would have the result that Leia no longer being in her custody, above assumed to be connected to her death, was something that happened before [nameless mother died].  It's even conceivable that [nameless mother] didn't die, but then there's a major question of where she ended up that she never contacted either of her children

I like the idea put forward in the other thread that [nameless mother] was a Jedi too.  Anakin's lightsaber was put in safekeeping so it could be given to Luke, [nameless mother's] was put in safe keeping so it could be given to Leia.  But by the time Leia was old enough the Jedi were basically exterminated and those who had kept the lightsaber didn't think it wise to give it to Leia for the same reason Corran Horn of the Expanded Universe was never told he could be a Jedi: If Leia had been told she would have been so proud she'd have difficulty keeping it a secret and a single wrong move could mean death.

There's absolutely nothing in the original Star Wars to contradict this, but there's also nothing to support it.  Absolutely nothing.

So, tangent over, one of the seven things listed above, or something like it, happened for Leia.

Meanwhile, back at the ranch, Obi-Wan clashes with Owen over how to deal with Luke.  Owen is afraid Luke will end up like his father (which whether you've heard the truth or the "certain point of view" is not a good way to end up) and tries to protect Luke from that.  Part of that involves telling Luke lies about his father, part of that involves keeping Obi-Wan away.  Part of it involves always finding one more thing for Luke to do around the farm before he can go away to make his own life.

At some point Obi-Wan, now Ben, determines that Luke is old enough to get his father's lightsaber.  Owen won't allow it.

Leia becomes a member of the Imperial Senate.

Rebel spaceships win their very first victory against the Galactic Empire during which rebel spies steal the death star plans.

Star Wars (the first movie) starts.

-

And that's the story told in the original trilogy.