enable webmin scheduled package updates in config file

I'm deploying webmin across many servers using Terraform & cloud-init. I want to enable "Scheduled Upgrades" in the "Software Package Updates" module during setup by using a config file template. I can successfully configure the action and reporting email by including the following in /etc/webmin/package-updates/config : sched_email=sys.admin@... sched_action=2 However, there seems to be no entry for the schedule interval selection and enabling it. What other config file (if any) is this info stored in? I've also tried using the webmin CLI but couldn't figure out the correct option name: # webmin set-config -m package-updates -o schedule -value 1 # Error: Option 'schedule' is unknown in module package-updates