change_house_relation_feud_score_effect

change_house_relation_feud_score_effect = {
	save_scope_as = house
	$TARGET$ ?= { save_scope_as = other_house }
	random_house_relation = {
		limit = {
			has_bp1_dlc_trigger = yes
			has_house_relation_level = feud
			any_relation_house = { scope:other_house ?= this }
		}
		save_scope_as = relation
		if = {
			limit = {
				exists = var:house_feud_house_1
				exists = var:house_feud_house_2
				exists = var:house_feud_house_1_score
				exists = var:house_feud_house_2_score
			}
			if = {
				limit = { var:house_feud_house_1 = scope:house }
				change_variable = { name = house_feud_house_1_score add = $VALUE$ }
			}
			else = {
				change_variable = { name = house_feud_house_2_score add = $VALUE$ }
			}
		}
		else = {
			set_variable = { name = house_feud_house_1 value = scope:house }
			set_variable = { name = house_feud_house_2 value = scope:other_house }
			set_variable = { name = house_feud_house_1_score value = $VALUE$ }
			set_variable = { name = house_feud_house_2_score value = 0 }
		}
		hidden_effect = {
			scope:house ?= {
				every_house_member = {
					limit = { is_ai = no }
					send_interface_message = {
						type = house_feud_$REASON$_good_message
						left_icon = scope:house.house_head
						right_icon = scope:other_house.house_head
						if = {
							limit = { $VALUE$ >= house_feud_major_counter_value }
							custom_tooltip = house_feud_tipped_scales_pos_big
						}
						else_if = {
							limit = { $VALUE$ >= house_feud_medium_counter_value }
							custom_tooltip = house_feud_tipped_scales_pos_medium
						}
						else = { custom_tooltip = house_feud_tipped_scales_pos_small }
					}
				}
			}
			scope:other_house ?= {
				every_house_member = {
					limit = { is_ai = no }
					send_interface_message = {
						type = house_feud_$REASON$_bad_message
						left_icon = scope:house.house_head
						right_icon = scope:other_house.house_head
						if = {
							limit = { $VALUE$ >= house_feud_major_counter_value }
							custom_tooltip = house_feud_tipped_scales_neg_big
						}
						else_if = {
							limit = { $VALUE$ >= house_feud_medium_counter_value }
							custom_tooltip = house_feud_tipped_scales_neg_medium
						}
						else = { custom_tooltip = house_feud_tipped_scales_neg_small }
					}
				}
			}
		}
	}
}

As written in game/common/scripted_effects/10_dlc_tgp_house_relation_scripted_effects.txt.