Runway: relationship sorting

I have two collections: 'Blog Posts' and 'Blog Authors.' In the Blog Posts template I'm using perch:related to relate the authors:

<perch:related suppress="true" order="7" id="authors" collection="Blog Authors" label="Authors" >
  <perch:content id="name" type="text" label="Name" required="true" title="true" /><perch:content id="slug" type="slug" for="name" />
  <perch:content id="twitter_name" type="text" label="Twitter Name" replace="@|" />
</perch:related>

This is working great, but my client needs to be able to sort the authors in order of importance (based on the contribution level of each author -- this is a research website). We're adding authors to the relationship field in the order that they should appear, but upon saving they're sorted alphabetically. How can I tell Runway the order in which the authors should appear?

Diagnostics (I'm two point releases behind, can't update at the moment)

HEALTH CHECK

Perch is out of date. You are running Perch Runway 2.8.32 and the latest is 2.8.34. Update instructions
PHP 5.6.24 is up to date
MySQL 5.5.52-cll is up to date
Image processing available
SUMMARY INFORMATION

Perch Runway: 2.8.32, PHP: 5.6.24, MySQL: mysqlnd 5.0.11-dev - 20120503 - $Id: 76b08b24596e12d4553bd41fc93cccd5bac2fe7a $, with PDO
Server OS: Linux, litespeed
Installed apps: content (2.8.32), assets (2.8.32), categories (2.8.32), collection_11 (2.8.32), collection_10 (2.8.32), collection_9 (2.8.32), collection_8 (2.8.32), collection_5 (2.8.32), collection_6 (2.8.32), collection_2 (2.8.32), collection_7 (2.8.32), collection_4 (2.8.32)
App runtimes: <?php $apps_list = array( 'content', 'categories', );
PERCH_LOGINPATH: /ifs-admin
PERCH_PATH: /home/mttstage/public_html/ifs/ifs-admin
PERCH_CORE: /home/mttstage/public_html/ifs/ifs-admin/core
PERCH_RESFILEPATH: /home/mttstage/public_html/ifs/ifs-admin/resources
Image manipulation: GD
PHP limits: Max upload 64M, Max POST 64M, Memory: 128M, Total max file upload: 64M
F1: 2edba60ed1f613d6dd804feb202456a2
Resource folder writeable: Yes
HTTP_HOST: ifs.staging.mytechtailor.com
DOCUMENT_ROOT: /home/mttstage/public_html/ifs
REQUEST_URI: /ifs-admin/core/settings/diagnostics/
SCRIPT_NAME: /ifs-admin/core/settings/diagnostics/index.php