parent_for_elective_succession_trigger

parent_for_elective_succession_trigger = { #This trigger is used to prevent grandchildren from being selectable when their parent is still available as a candidate.
	this != scope:holder #Not the current ruler.
	dynasty = scope:holder.dynasty
	is_child_of = scope:holder

	OR = {
		is_female = no
		scope:title = {
			NOT = { has_title_law = male_only_law }
		}
	}
	OR = {
		is_female = yes
		scope:title = {
			NOT = { has_title_law = female_only_law }
		}
	}

	OR = { #Candidate should not be a landless Courtier that is about to inherit a Theocracy or Republic
		AND = {
			is_available_quick = {
				ruler = yes
				advanced_ruler = yes
			}
			has_unelectable_government_trigger = no
		}
		NOT = {
			any_heir_title = {
				holder ?= {
					has_unelectable_government_trigger = yes
				}
			}
		}
	}
	OR = { #If the title controls the faith, candidates must be of the same faith.
		scope:holder = {
			NAND = {
				exists = faith.religious_head
				this = faith.religious_head
			}
		}
		faith = scope:holder.faith
	}
	has_unelectable_trait_trigger = no
	has_unelectable_government_trigger = no
}

As written in game/common/scripted_triggers/00_elective_triggers.txt.