migration_title_and_vassal_change_effect

migration_title_and_vassal_change_effect = {
	scope:domain ?= {
		if = {
			limit = {
				tier = tier_county
			}
			holder = {
				add_to_list = old_holder
			}
		}
		else = {
			every_de_jure_county_holder = {
				limit = {
					is_independent_ruler = yes
				}
				add_to_list = old_holder
			}
		}
	}
	scope:target_title.holder ?= {
		add_to_list = old_holder
	}

	# Change 1: The old holder will attempt to create a new title for their lands, if they are losing their primary title
	every_in_list = {
		list = old_holder
		# Inform relevant people
		migration_message_effect = yes
		# Run effects
		migration_find_fitting_title_effect = yes
	}

	# Change 2: Hand out titles to actor
	create_title_and_vassal_change = {
		type = migration
		save_scope_as = change1
		add_claim_on_loss = yes
	}
	scope:target_title ?= {
		change_title_holder = {
			holder = scope:actor
			change = scope:change1
		}
	}
	if = {
		limit = {
			NOT = { scope:domain = scope:target_title }
		}
		scope:domain = {
			change_title_holder = {
				holder = scope:actor
				change = scope:change1
			}
		}
	}
	if = {
		limit = {
			scope:domain.tier = tier_duchy
		}
		scope:domain = {
			every_de_jure_county = {
				change_title_holder = {
					holder = scope:actor
					change = scope:change1
				}
			}
		}
	}
	if = {
		limit = {
			scope:target_title.tier >= tier_kingdom
		}
		scope:target_title ?= {
			every_in_de_jure_hierarchy = {
				continue = {
					tier >= tier_duchy
				}
				limit = {
					holder ?= {
						OR = {
							any_in_list = {
								list = old_holder
								this = prev
							}
							this = scope:recipient
							AND = {
								scope:recipient = this.liege
								any_held_county = {
									is_landless_type_title = no
									NOT = { target_is_de_jure_liege_or_above = scope:target_title }
								}
							}
						}
					}
				}
				change_title_holder = {
					holder = scope:actor
					change = scope:change1
				}
			}
		}
		scope:target_title = {
			every_de_jure_county_holder = {
				limit = {
					OR = {
						any_in_list = {
							list = old_holder
							this != prev
							this = prev.liege
						}
						AND = {
							this != scope:recipient
							scope:recipient = this.liege
						}
					}
					this != scope:actor
				}
				add_to_list = new_vassals
			}
		}

As written in game/common/scripted_effects/09_dlc_mpo_scripted_effects.txt.