How is Barbossa one of the Eight Lords of the Brethren Court?

Question

From what I have understood, this is how the timeline was at the 3rd movie (Lot's of spoilers from the 1st, 2nd and 3rd movies):

Before the first movie, Hector Barbossa was recruited by Jack Sparrow as boatswain. Then he convinced Jack Sparrow to share the location of the Aztec Treasure. After that,

he abandoned Jack Sparrow on an island and went for the treasure with the rest of the crew.

Then, they all take at least one piece of gold and

William Turner Sr. sent one piece to his son, who was living in (England?).

And somehow, neither

Will Jr. nor his mother sold it.

1 or 2 years later Will Jr. decides to go to the Caribbean. He's the only survivor after the ship he was travelling was attacked by pirates.

From when the crew of the Black Pearl found the Aztec Treasure,

William Turner Sr. keeps complaining about having left Jack on that Island. After he sends the gold piece to his son, the crew gets tired of him and they tie a cannonball to his feet and they throw him overboard, where he meets Davy Jones and becomes a member of his cursed crew.

After that, the crew of the Black Pearl go on a crusade across the world looking for

the aztec gold pieces and taking any other gold they can reach, taking advantage of their cursed-immortal state.

Then we jump to the future to the plot of the first movie

where Barbossa dies.

In the third movie we see that

Hector Barbossa was one of the Lords of the Brethren Court (understandable given that he was immortal up until some years ago)

However, how was he able to claim one of the pieces of eight?

Unless he was an undercover Pirate Lord when he initially joined Jack's crew (difficult, since Jack would have recognised him), or he stole the piece from some other Pirate Lord while he was in his undead rampage, he couldn't be part of the Court.

Is that explained anywhere or is it a plot hole?

Answer 1

This is answered in the novel Pirates of the Caribbean: The Price of Freedom. Barbossa becomes a Pirate Lord after he is given one of the Pieces of Eight, which eventually becomes Ragetti's wooden eyeball, by Captain Boris 'Borya' Palachnik.

During the events of the novel Barbossa's ship, Cobra, was destroyed by Borya. After Jack and Barbossa track down Borya he is found to have broken the Code of the Brethren and is sentenced to death. As part of his last meal and drink he requests Barbossa join him. During this time Borya bestows his ship, Koldunya, and a wooden block, Borya's Piece of Eight, thus making Barbossa a Pirate Lord.

"...Seems Borya had the sinking of me Cobra on his conscience, and he wanted me t’ know he was sorry for it. Apologized most sincerely, he did. Cap’n Teague was there, as witness, and he told him that if the Pirate Lords agreed, he thought Koldunya should be passed on to me, so I wouldn’t be a cap’n without a vessel. That’s like bein’ a fish with no water, he said” Barbossa sighed. “We used to be good friends, once, I told you that, Jack.”

[...]

“I could hardly believe it meself. Oh, and he gave me this, said it was his most precious token. His mind must be addled, is all I can say.” Reaching into his coat, Barbossa fumbled for a moment, and brought out a small, square block of wood, about an inch and a half on the side.

Jack looked at it, then looked sideways at Esmeralda. She was staring at it, wide-eyed. As she caught Jack’s gaze, she nodded, as if confirming his unspoken question.

_{Pirates of the Caribbean: The Price of Freedom - Chapter 10}

While Barbossa doesn't seem to realise what this wooden block is, Jack certainly does and advises him to take it to Captain Teague:

“You need to be careful of that little token,” Jack said. “Don’t lose it. Show it to Captain Teague as soon as you can. He’ll tell you what it is.”

Barbossa turned the little block over in his fingers. “You say this is important? Looks like junk.”

“It is important, Hector. Unless I’m much mistaken, that is one of the Nine Pieces of Eight.”

Barbossa frowned. “And what might those be, Jack?”

“They’re important,” Jack assured him. “Teague will explain.”

_ibid

Nothing really happens from this point on in the novel concerning Barbossa. We don't see his conversation with Borya nor Teague.

Borya and his crew manage to escape their cells thanks to the help of

Christophe.

After some time and a fast-paced action sequence Koldunya, and Borya with her, are subsequently blown up by Jack and the crew of the Wicked Wench, meaning Barbossa is bereft of his newly bestowed ship.

Being given a Piece of Eight by one of the Pirate Lords is enough to make one a Pirate Lord, and thus Barbossa inherits the title of "Pirate Lord of the Caspian Sea", despite not having a ship to be captain of.