Optional missions from your underbosses have five instances. You unlock one instance by default, and two instances per district assigned. So to get all optional mission instances for all your underbosses, you have to divide the 9 districts (the Bayou is free) equally among them. Equally dividing the districts also ensures that they'll remain loyal to you and won't rebel against you. Loyalty is also increased by completing these optional missions for them.
Talk to Vito to trigger a cutscene. You’ll have to interrogate Lucky’s old cronies. You don’t need to interrogate all of them. Just one of them will be enough to reveal the location of Vito’s target. Once revealed, head to the location and make your move on the target. You can go guns blazing or stealth kill them one by one. One of the easiest ways of killing him is by breaking the lock of the backdoor silently in the Auto-service shop he's staying then throw a grenade or molotov at him. Once done, talk to Vito to complete this mission.
After assigning a district to Vito, talk to him again to continue with this mission. He’ll ask you to hunt down Nestor the Molester.
To know his location, you have to interrogate any one of his old crew. You’ll have the option to recruit one of them to add to your racket or kill them. After the interrogation, Nestor’s location will be revealed. Head there and make your move.
Nestor is staying at his garage with a handful of guards. You can lure and pick off the sentry in the alley then when you have a clear shot, you can snipe his head off. You don’t need to take out his guys but nothing is stopping you either. Once done, report to Vito to complete this hit.
After completing the second hit for him, you can talk to him again to start another hit. He’ll ask you to go after Pauli Biancardi this time. Make your preparations and head to the location. He’s located in a cemetery. The easiest way to kill him is to snipe him from afar. Eliminate his guards with stealth kills until you get close enough and get a good view where you can pick him off with a rifle.
After assigning the third district to Vito, talk to him to know the next target. For this target, you have to interrogate one of the three members of his crew.
In this walkthrough, we targetted Heath Matarazzo. He's in the open with two other guys. You can lob a grenade or molotov to kill the other two out and disable him. Walk to him and interrogate him to reveal your target's location.
After interrogating one of them, Luca Gudi’s location will be revealed in the map. Head there and make your move. You can pick off his men from afar using a sniper rifle. There are no witnesses here so you can make all the noise you want. There’s a sniper on the roof of a establishment beside his hideout so you can take that out as well. Once you thinned his numbers enough, you can go in with guns blazing or continue sniping them until they’re wiped out. Report back to Vito to complete this instance and get the last target on his list.
Dario Murtas is the name of the next target. He is immediately marked in the map without the need for interrogation. Head to the marked location and carefully swim across. This is a small island with lots of cover and space to move around. When Sneaking in, I suggest taking out the sniper from the tower by the docks first. Next, stealth kill most of his men then engage them in a firefight in you want. Dario is really well guarded so you have to rely on your intel view to keep track of their positions. You can snipe Dario over the fence if you want, as long as they’re not aware. Also, as long as you get rid of any immediate enemy, he should be walking around his shack searching. However, he won’t leave the compound.
After the job’s done, head back to Vito and talk to him to fully complete his optional mission and earn the corresponding trophy.