Move billing address fields to after a specified PMPro checkout box at checkout.

my_pmpro_move_billing_fields.php

<?php

// Copy from below here...

/*
 * Move billing address fields to after a specified PMPro checkout box at checkout.
 */
function my_pmpro_move_billing_fields() {
	global $pmpro_pages;
		if(is_page($pmpro_pages['checkout'])) {

		?>
		<script>
			jQuery( '#pmpro_billing_address_fields' ).appendTo( '#pmpro_checkout_box-personal' );
		</script>
		<?php
		}
}
add_action( 'wp_footer', 'my_pmpro_move_billing_fields' );