Hi Waukeag,
I am sorry for the inconvenience.
The plugin only shows up on the Network Admin page.
Please also make sure you have our free version installed to be able to use the Multisite Extension.
Yes, you can import a single site into your network without overwriting the entire network.
How our Multisite Extension works is for you to import the file on the Network Admin page and the plugin will create a new site for you.
You will be asked to specify a subsite name once the file upload completes and you click “Continue”.
You can write to me directly to support at servmask.com since our Multisite Extension includes premium support.