Important Note: I am aware of this post regarding NPC training but it failed to answer my question and the top answer has some holes.
I want to run a heavily player-based, sandbox campaign (I am aware of the difficulties) and to help the players get started I decided to use Waterdeep: Dragon Heist as a way for them to get experience and money.
With that said I decided to give my players infinite choices (essentially I allow them to do as much as they can physically and mentally achieve). Consequently one of the most engaged players in the party, a Rogue level 4 (soon to be 5), decided he wanted to start a hitman business.
He managed to steal a bank and he used that as a way to disseminate a message via a local newspaper agency. The message advertised the hitman business and included directions for when and where to meet him if interested.
That much about the backstory. Now, the issue is that he wants to "train" NPCs (Bandits) to turn them into Assassins.
He told me he wants them to be able to use Sneak Attack (the Rogue's ability) but he also wants their Dexterity and Charisma modifiers to be higher than normal.
I was wondering, is there an official ruling that can assist me with NPC progress (type change more specifically)
If so, what are the limitations/prerequisites for that to happen?
At the beginning of the post I linked a very similar thread. Though it failed to answer my question so I decided to repost.
I should note that the aforementioned post did not answer the question Can it be achieved, if yes how? I am trying to find a way to change an NPC's type from Bandit to Rogue. Another issue with the answer is that the player is not a trainer/teacher in any way. He has never trained anyone in his entire life which I imagine is a setback. Then, the answer states:
So, provided your PC is sufficiently skilled to offer "special" training, it would seem that they can impart some level of skill to the peasants.
In what level can a player be considered sufficiently skilled to offer training (as a mean to change the NPC's type)?
What is 'some level of skill'? Does this mean that an NPC cannot learn the Sneak Attack ability or does it mean that there is going to be a significant setback?
Note: As there has been confusion regarding what it is specifically that I am asking: I am asking for a way for a PC to change an NPC's 'class'/type. In my case from Bandit to Rogue. I am looking for personal experiences with similar scenarios using official ruling, if possible. It is true that I can try and come up with a system myself but I want to know if a system like that already exists.