Exchange 2016 iApp

I don't know if the iApp has the functionality you are looking for, but I will give you generic advice about iApps.

If you are using iApps, just perform changes from the iApp itself (reconfiguring the iApp). You need to disable strict updates, to be able to make manual changes. If you get a new iApp template, either via system upgrade or manually download the template, your manual configurations will be lost after you update the iApp to use that template.

Resuming, reconfigure the iApp and try the configuration within the iApp itself. Only in case the iApp does not has the functionality, do manual changes (and document the changes).