UPT upt_user_choices filter

<?php
/** create include only list to narrow available choices of user meta to sync
 ** in UPT.  You still have to check and save them in the UPT admin page,
 ** this just changes options available to select
 **/

add_filter( 'upt_user_choices', function( $choices ) {

    // array of custom user meta fields to display in dropdown list
	$include = [ 'billing_address_2', 'billing_address_1'];

	foreach ( $choices AS $key => $value ) {
		if ( 0 === strpos( $key, 'meta-') & ! in_array( $value, $include) ) {
			unset( $choices[ $key ] );
		}
	}

	return $choices;
});