This is updated version of DefectionOverhaul for MCMv3 and Bannerlord as of July 5th, 2020.

Original Mod: https://www.nexusmods.com/mountandblade2bannerlord/mods/705

Current Source code: https://github.com/chinux23/Reform/tree/master/DefectionOverhaul

The goal of this mod is to prevent clans from defecting from or leaving the player's kingdom, unless the leader's relationship with the player is low (threshold is configurable). I got tired of clan leaders I had a positive relationship with, or had given fiefs to etc, still defecting from my Kingdom.

This is achieved with a Harmony Prefix patch of the following methods found in TaleWorlds.CampaignSystem.SandBox.CampaignBehaviors.BarterBehaviors.DiplomaticBartersBehavior:

ConsiderDefection(Clan, Kingdom)
ConsiderClanLeaveKingdom(Clan)
ConsiderClanLeaveAsMercenary(Clan)

The Harmony patch applies logic that prevents these methods from running for a clan that is in a Kingdom where the ruling clan is the player's clan, with a leader whose relationship is above a configurable threshold with the player. How Honorable the clan leader is affects the threshold. Otherwise, the methods run as normal and the clan may leave the Kingdom. The minimum required relationship with the player is adjustable in the Mod Options menu. There is also three global toggles for whether all clans are allowed to defect from/leave/leave as mercenary. This applies to clans in every Kingdom, not just the player's, and overrides any other settings set in the mod - this is Disabled by default.

Known Compatibility Issues

• The Community Patch should be placed before Native (very top, load first).
• Defection Overhaul has been tested on version 1.4.2
  

Potential Future Features

• Open for suggestions
  

Tools Used
Harmony Library - https://github.com/pardeike/Harmony
Mod Configuration Menu v 3 - https://github.com/Aragas/Bannerlord.MBOptionScreen