Hide specific sites from The Hub

We use The Hub as a management tool for sites we built and/or maintain for our clients, who pay for this service. This works great.

However, sometimes it's necessary for us to install a specific WPMU Dev plugin like Smush Pro, Defender Pro or Snapshot Pro on a site of a client that's not making use of our maintenance 'package', which is a choice they can make.

To install premium WPMU plugins, we need to connect the WPMU Dashboard to the site, which means the site will appear in our management tool (The Hub). This would be fine if there's a way to hide these sites, or group them so they are apart from the sites which we are actively maintaining.

I know there's a workaround for Smush Pro, by adding your API key to the wp-config.php file. This is an acceptable workaround, but as mentioned: it's only working for Smush Pro.

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This is the line, in case people would be looking for that:
define( 'WPMUDEV_APIKEY', 'YOUR-API-KEY');
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