Pairing a device without physical access

TLDR

Can someone confirm: If the initial paired phone is on the same network as the Firewalla, can I send a QR code to pair a second phone which only has access to the device directly over the internet?

Context

I am looking for a device to help support and manage the home network of my parents-in-law. I would tentatively like to send them a Blue+ and get a Gold for myself. I'm trying to figure out how to deploy successfully to their home, from across the country.

I found instructions for adding a second app (https://help.firewalla.com/hc/en-us/articles/115004369774-Tutorial-Managing-a-Firewalla-by-multiple-Apps), but they aren't clear. One sentence mentions "the phone can be paired remotely" and another sentence mentions "MDNS entries which were used to check if your phone is on the same network as Firewalla."

It would be great if that article was updated with details making it clear which connectivity scenarios are supported.

Possible Scenarios

One option is to try to pre-pair the device. It sounds like this might be possible if I pre-configure a router at my home to match the network settings of their router (which I will need to figure out). I can then pair the device locally, ship it to them, have them plug it in and hope everything just works.

The alternative scenario is to just ship them an unpaired / unconfigured device. As long as everything works in Simple mode, I can hopefully talk them through the initial setup process and then have them add me as a second manager for the phone. However, this hinges on remote-pairing functionality working.

Would love to hear any thoughts or best practices folks have for achieving this goal!