Into the squad have come batters Saim Ayub and Abdullah Fazal, both possessing previous Test experience.
Five uncapped players have also been called up: spin-bowling all-rounder Arafat Minhas, left-arm seamer Mohammed Imran Jr, wicketkeeper Said Baig and all-rounders Mohammad Imran and Razaullah.
“When I took over, three players had already left the squad – Rizwan, Imam and Salman Ali Agha,” said Hesson. “From there it was a matter of trying to get a balanced squad for the third Test.
“I don’t think anyone wants these to happen in the middle of a series, clearly not.
“From my perspective, it’s about putting a balanced squad together, not only for this Test, so we actually have some variety in our attack.
“Pakistan is known for the pace, unusual actions, mystery spin – we haven’t really been able to present any of that.”
On Friday, Pakistan trained at the indoor centre at Edgbaston because of wet weather in Birmingham. Four of the new arrivals trained with the squad, with three more due to link up later in the day.
Hesson also hit back at reports that Salman refused to attend the meeting with King Charles after being dropped.
Salman, Pakistan’s T20 captain under Hesson, led the Test side in the series opener at Headingley because of an injury to Babar Azam, then was left out of the XI for the second Test before being omitted from the squad entirely.
Hesson said Salman did not attend the audience with the King because he was part of the trio of players dropped from the squad first and, as a result, Salman, Imam and Rizwan were taken from the list of attendees to Clarence House.
A Pakistan official then confirmed that the four players dropped after Hesson’s arrival were still able to meet the King.
“I know there’s been a void in news, but people are just making up stories,” said Hesson.
“Three players were released from the squad before I arrived and well before [meeting the King]. They were sent a note at the time that these three players will not be attending.
“Someone has just made something up. All of the rest of the players in the squad were already on the list. I was on the list as the white-ball head coach. There has been no changes to it.
“Someone has put two and two together and come up with nine. For me, that’s unacceptable journalism.”