add address_field_2 in correct location

address_field_2.php

<?php

add_filter( 'woocommerce_checkout_fields' , 'custom_override_checkout_fields', 9999 );
function custom_override_checkout_fields( $fields ) {

	$address_2 = array(
		'placeholder' => __('Appartment, suite, unit etc.(optional)', 'woocommerce'),
		'label' => __('Appartment, suite, unit etc.', 'woocommerce'),
		'class' => array('form-row-wide', 'address-field'),
		'required' => false,
		'autocomplete' => "address-line2",
		'priority' => 60
	);
	
	$new_fields = array();
	/*billing fields*/
	foreach( $fields['billing'] as $key => $value){
		$new_fields[$key] = $value;
		if($key == 'billing_address_1'){
			$new_fields['billing_address_2'] = $address_2;
		}
	}
	$fields['billing'] = $new_fields;

	$new_fields = array();
	/*shipping fields*/
	foreach( $fields['shipping'] as $key => $value){
		$new_fields[$key] = $value;
		if($key == 'shipping_address_1'){
			$new_fields['shipping_address_2'] = $address_2;
		}
	}
	$fields['shipping'] = $new_fields;

	return $fields;
}