Offer Confederation

is_available = OR = {
	government_has_flag = government_is_tribal
	government_has_flag = government_is_nomadic
}
trigger_if = {
	limit = {
		is_ai = yes
	}
	OR = {
		is_confederation_member = yes
		AND = {
			has_character_flag = forming_confederation
			highest_held_title_tier < tier_kingdom
			is_independent_ruler = yes
		}
	}
	age >= 6
}
is_playable_character = yes
OR = {
	is_independent_ruler = yes
	confederation ?= {
		is_house_based = no
	}
}
is_shown = scope:recipient = {
	is_playable_character = yes
	is_independent_ruler = yes
	OR = {
		government_has_flag = government_is_tribal
		government_has_flag = government_is_nomadic
	}
	NOT = {
		this = scope:actor
	}
}

As written in game/common/character_interactions/09_mpo_interactions.txt.

trigger_if = {
	limit = {
		scope:actor = {
			is_confederation_member = no
		}
	}
	custom_tooltip = {
		text = forming_confederation_tt
		scope:actor = {
			has_character_flag = forming_confederation
		}
	}
}
scope:actor = {
	is_imprisoned = no
}
scope:recipient = {
	valid_confederation_member_trigger = {
		CHARACTER = scope:actor
	}
	is_imprisoned = no
	is_at_war = no
}

As written in game/common/character_interactions/09_mpo_interactions.txt.

on_accept = if = {
	limit = {
		scope:recipient = {
			is_playable_character = yes
		}
	}
	scope:actor = {
		if = {
			limit = {
				has_character_flag = forming_confederation
			}
			remove_character_flag = forming_confederation
			if = {
				limit = {
					is_ai = no
				}
				add_achievement_global_variable_effect = {
					VARIABLE = mpo_confedup_achievement_unlocked
					VALUE = yes
				}
			}
		}
	}
	if = {
		limit = {
			scope:recipient = {
				is_at_war_as_defender = yes
				any_character_war = {
					is_war_leader = scope:recipient
					is_defender = scope:recipient
				}
			}
		}
		scope:recipient = {
			every_character_war = {
				limit = {
					is_war_leader = scope:recipient
					is_defender = scope:recipient
				}
				add_to_list = recipient_wars
			}
		}
		every_in_list = {
			list = recipient_wars
			save_scope_as = recipient_war
			primary_attacker = {
				save_scope_as = attacker
			}
			add_defender = scope:actor
			hidden_effect = {
				scope:actor.confederation ?= {
					every_confederation_member = {
						limit = {
							NOR = {
								is_attacker_in_war = scope:recipient_war
								is_defender_in_war = scope:recipient_war
								is_at_war_with = scope:recipient
								is_allied_to = scope:attacker
								is_imprisoned_by = scope:recipient
								is_at_war_with = scope:recipient
							}
						}
						scope:recipient_war = {
							add_defender = prev
						}
					}
				}
			}
		}
		if = {
			limit = {
				scope:actor.confederation ?= {
					any_confederation_member = {
						NOR = {
							is_attacker_in_war = scope:recipient_war
							is_defender_in_war = scope:recipient_war
							this = scope:actor
							is_at_war_with = scope:recipient
							is_allied_to = scope:attacker
							is_imprisoned_by = scope:recipient
							is_at_war_with = scope:recipient
						}
					}
				}
			}
			scope:actor = {
				custom_tooltip = confederates_joining_recipient_war_tt
			}
		}
	}
	scope:actor = {
		save_scope_as = confederation_offerer
	}
	scope:recipient = {
		save_scope_as = confederation_accepter
	}
	if = {
		limit = {
			scope:actor = {
				is_confederation_member = no
			}
		}
		scope:actor = {
			custom_tooltip = create_confederation_tt
			custom_tooltip = confederation_defensive_wars_tt
			custom_tooltip = unlock_leave_confederation_interaction_tt
			if = {
				limit = {
					government_has_flag = government_is_nomadic
				}
				add_character_modifier = {
					modifier = mpo_confederation_member_modifier
					years = 5
				}
				capital_county ?= {
					change_county_fertility = major_county_fertility_level_gain
				}
			}
		}
		scope:recipient = {
			offer_confederation_accepter_effect = yes
		}
	}
	else = {
		scope:actor.confederation = {
			save_scope_as = confederation
		}
		show_as_tooltip = {
			scope:recipient = {
				offer_confederation_accepter_effect = yes
			}
		}
	}
	if = {
		limit = {
			scope:recipient = {
				government_has_flag = government_is_nomadic
			}
		}
		scope:recipient = {
			add_character_modifier = {
				modifier = mpo_confederation_member_modifier
				years = 5
			}
			capital_county ?= {
				change_county_fertility = major_county_fertility_level_gain
			}
		}
	}
	if = {
		limit = {
			scope:recipient = {
				is_ai = no
			}
		}
		scope:recipient = {
			custom_tooltip = confederation_raiding_attacking_tt
			if = {
				limit = {
					government_has_flag = government_is_nomadic
				}
				custom_tooltip = confederation_restrictions_warning_tt
			}
			else = {
				custom_tooltip = confederation_restrictions_tribe_warning_tt
			}
		}
	}
	scope:recipient = {
		if = {
			limit = {
				government_has_flag = government_is_nomadic
			}
			custom_tooltip = confederation_migrating_leaving_warning_tt
		}
	}
	scope:actor = {
		trigger_event = mpo_interactions_events.0001
	}
	if = {
		limit = {
			scope:actor = {
				is_at_war_as_defender = yes
				any_character_war = {
					primary_defender = {
						OR = {
							this = scope:actor
							AND = {
								exists = scope:actor.confederation
								is_member_of_confederation = scope:actor.confederation
							}
						}
					}
					is_defender = scope:actor
					NOR = {
						any_war_attacker = {
							is_allied_to = scope:recipient
						}
						any_war_attacker = {
							this = scope:recipient
						}
						any_war_defender = {
							this = scope:recipient
						}
						any_war_attacker = {
							scope:recipient = {
								has_truce = prev
							}
						}
					}
				}
			}
		}
		scope:actor = {
			every_character_war = {
				limit = {
					primary_defender = {
						OR = {
							this = scope:actor
							AND = {
								exists = scope:actor.confederation
								is_member_of_confederation = scope:actor.confederation
							}
						}
					}
					is_defender = scope:actor
					NOR = {
						any_war_attacker = {
							is_allied_to = scope:recipient
						}
						any_war_attacker = {
							this = scope:recipient
						}
						any_war_defender = {
							this = scope:recipient
						}
						any_war_attacker = {
# … (cut here; the rest is in the file)

As written in game/common/character_interactions/09_mpo_interactions.txt.