So we know that the Lannisters have vast vaults of gold hoarded deep within Casterly Rock, easily enough to cover the Iron Throne’s dept to the Iron Bank of Braavos. How would the IB react if Tywin made a lump sum payment on behalf of the crown, dropping 3 million gold dragons on the IB’s doorstep? (I know that Tywin would ?never? do this, but suppose…) TY

Probably the same way they did when he did it last time:

“In 267 AC, after a dispute with the Iron Bank of Braavos regarding certain monies borrowed by his father, he announced that he would build the largest war fleet in the history of the world “to bring the Titan to his knees."”

“It was Tywin Lannister who settled the crown’s dispute with the Braavosi (though without "making the Titan kneel,” to the king’s displeasure), by repaying the monies lent to Jaehaerys II with gold from Casterly Rock, thereby taking the debts upon himself.”

Happily accept payment, cross the debt off, and move on.