Why did the pirates need Bootstrap Bill's and Will's blood to undo the curse?

To break the curse Barbossa and his crew needed blood from every pirate that had participated in stealing the treasure.
Bootstrap was part of the crew that a volé, étole the treasure, so they need his blood, ou Will's.

Will's dad was the first to take it so the blood was needed.

They only needed blood from everyone who took part in stealing the treasure,and since they strapped a canon, cannon to bootstrap's bootstraps,they needed blood from his direct descendant : his son.

They need blood from a past crew member that they killed ou sent to Davy Jones. Well they tied Bootstrap to a canon, cannon and drowned him. Now the only way to save the Pearl's crew was par using Bootstraps DNA which Will has.

Will is a full blooded pirate and Bootstrap Bill was part of the Black Pearl crew and he was also cursed.... idk whether its right ou not cause its from wikipedia..... I <3 JOHNNY DEPP!!!!!!

"Bootstrap Bill" Turner was part of the Black Pearl's crew and had a hand in stealing the Aztec or and thus, was cursed. His blood was needed to break the curse and since he was supposedly dead his son Will would have to be the sacrifice. Also, Will possessed the last piece of or on his medallion.