Do NPC lords have benefits from taking prisoners?

[McKannister]

Hello, I heard that lords have their own money which they use to recruit and upgrade their troops, so I'm wondering if they make profits from leaving prisoners in castles and cities bacause their number is decreasing with time, but when they leave them in my city, i can just take them and sell to nearby ransom broker. Does anybody know the answer?

 

[Tasak]

The answer lies in the source code. There might be a script that does what you wrote, so who knows?