I carry several networks and when I joined BluesNet I created a Netmail area for it. For some reason, after I added the new area, the other Netmail areas were no longer associated with the correct network. No matter how many times I corrected it, they were still pointing to the wrong network.
You should only need a single netmail area for all networks and Mystic does the rest.
If you do want to use a specific netmail base for each network you should be able to, but you have to make sure you have it set to "Base Type: Netmail" and then each Netmail base you create for each network has to have the "Net Address" field set to your network address for that specific network.
... You can learn many things from children... like how much patience you have --- Mystic BBS v1.12 A48 2022/01/28 (Windows/64)
* Origin: Sector 7 * Mystic WHQ (1:129/215)