give_new_noble_family_title_effect

give_new_noble_family_title_effect = {
	if = {
		limit = {
			is_house_head = yes
			government_allows = noble_families
			trigger_if = {
				limit = {
					government_has_flag = government_has_county_tier_noble_families
				}
				highest_held_title_tier >= tier_county
			}
			trigger_else = { highest_held_title_tier >= tier_duchy }
			liege = {
				government_allows = noble_families
			}
			trigger_if = {
				limit = { any_held_title = { is_noble_family_title = yes } }
				has_domicile = no
			}
		}
		create_noble_family_effect = { GOVERNMENT_GIVER = this }
		domicile ?= { set_up_domicile_estate_effect = yes }
	}
}

As written in game/common/scripted_effects/00_administrative_effects.txt.