After doing a lot of investigating I finally found how to add investiture to a religion that isn't catholic or fraticelli.
In the religion file you need to add "investiture = yes" to your desired religion.
Then you need to edit "succession_laws.txt" in common/laws/ directory. You need to edit "succ_open_elective" and "succ_catholic_bishopric" sections.
In "succ_open_elective" you should exclude your desired religion like how you see catholic and fraticelli is in the potential scope.
Code:
OR = {
is_landless_type_title = yes
holder_scope = { is_theocracy = no }
holder_scope = {
NOT = { religion = catholic }
NOT = { religion = fraticelli }
}
}
Then in "succ_catholic_bishopric" allow your religion into the potential scope in the same section that catholic and fraticelli is.
Code:
potential = {
is_landless_type_title = no
OR = {
AND = {
tier = baron
is_theocracy = yes
}
holder_scope = { is_theocracy = yes }
}
holder_scope = {
OR = {
religion = catholic
religion = fraticelli
}
is_merchant_republic = no
OR = {
independent = yes
is_feudal = no
NOT = {
any_liege = {
holy_order = yes
}
}
}
}
Then in "crown_laws.txt" do basically the same thing. Just include your religion under the "investiture_law_1" code where you see catholic and fraticelli
Code:
investiture_law_1 = {
show_as_title = yes
rel_head_opinion = -30
free_invest_vassal_opinion = 10 # vassals with bishops will appreciate this law
temple_all_opinion = 10 # Bishops will tend to be more loyal to the Crown
group = investiture_law
potential = {
holder_scope = {
OR = {
religion = catholic
religion = fraticelli
}
is_tribal = no
is_nomadic = no
NOT = {
rightful_religious_head_scope = {
character = ROOT
}
}
}
}
What all of this does is allow your religion to have investiture, and tells the game any bishop titles that are controlled by your religion is not allow to have open elective succession (the succession type of mayors) and that the next available succession type is the catholic bishop succession.
So here is the part that a lot of people get stuck on. How to add it in mid game.
Open up your save game and find your primary title. then add " law="investiture_law_1" " into the laws sections of your title. Make sure to put it in the exact spot you see below, cause if you put it out of order or else where, when you open up the religion tab the nominate button will be grayed out.
Code:
k_persia=
{
holder=2608670
succession=tanistry
gender=true_cognatic
law="centralization_0"
law="law_voting_power_0"
law="war_voting_power_0"
law="revoke_title_voting_power_0"
law="imprison_voting_power_0"
law="grant_title_voting_power_0"
law="banish_voting_power_0"
law="execution_voting_power_0"
law="revoke_title_law_0"
law="vassal_wars_law_0"
law="tax_levy_law_feudal_4"
law="tax_levy_law_republic_4"
law="tax_levy_law_theocracy_4"
law="tax_levy_law_tribal_4"
law="investiture_law_1"
law="succ_tanistry"
law="vice_royalty_0"
law="succession_voting_power_0"
law="out_of_realm_inheritance_law_0"
law="ze_administration_laws_1"
law="true_cognatic_succession"
So one of the issues you will find is that after doing all of that, none of your bishop titles show up under your religion tab. This is because right now all of your bishop titles have some other succession type instead of the "succ_catholic_bishopric" succession type. Sadly there is no quick any easy way to fix this via just save game editing. Cause there is no way to quickly just change all your bishop titles to "succ_catholic_bishopric" since most of them probably show up as "succ_open_elective" which is the same type of succession cities and holy orders have, so you can't just search and press replace all in notepad++. Though whenever the ownership of the title changes, as in when it gets transferred to the next holder, the game reevaluates what type of succession is valid for the title. So whenever your bishop dies or abdicates the title, the game will automatically change the title to "succ_catholic_bishopric", which will then finally let you nominate the next successor.
So there is a couple ways you can go about to fixing this.
1. You can go about killing all your of bishops or revoke all the titles or demanding that the convert to your religion which will cause a new NPC to usurp the bishop title from the current holder and change the succession type. You can also cheat and use console commands to change your bishops religion manually.
2. Create a cheat decision that toggles all your bishops religions to yours, then in game use the console to change your religion to a different religion, use the decision to change your bishops to your religion which causes the game to generate all new bishops with the new religion, then change your religion back to your desired religion, then use the decision again which then causes the game to generate all new bishops with your desired religion with the right succession type now. As you can see the down side of this is you lose all of your current bishop vassals who then go to all random courts. So if you have any bishop vassals you like in particular make sure you note them down before you do this and just use the "move" console command or decision in the "sketchy cheat menu" mod to take back the vassals / courtiers that you like and would like to nominate.
3. Be lazy and just search for what your bishop title's succession type is, and just hit replace all on it with "succ_catholic_bishopric" in your save game file. This will mess up the succession of all the cities, temples, and holy orders for everyone, and allow you to even nominate your current mayors' successors one time. Then in theory the game should fix itself after the current holder of whatever title's succession you just messed up dies or abdicates when the game re-checks for valid succession types.