Setup same access key for subdomain

Hi there – just signed up today.

I gather if I use subdomains I can use one access key for the “parent” domain and any of its subdomains?

If so…

1) How do I do that, please? If I add a new subdomain website via your portal it gets a unique key, so I’m guessing that’s not the way to do it. I have also tried to change the subdomain’s access key (to match the main domain) in its plugin settings (via show access key). It let me do that and save it, but on the portal the key shown there is the original key and not the “shared” one?

2) I also thought perhaps, when installing the plugin, maybe I should choose the “manual” option. However, there’s no way I can see to “reset” the plugin (so I can see the manual setup option again)? If I deactivate and delete, and re-install the plugin, it retains the original set up. So how do I “reset” the plugin?

3) Regardless of the above, and assuming I can get this to work – am I then right that if I have a 5-site package, and I have 5 sites registered, and one of those sites has 3 subdomains – provided I use the same key for that one site and its 3 subdomains, the 5-site package covers those 8 sites?

Many thanks, in advance.

Adam