I just tried to send a test post to a label, but there was no way to add which subscribers to send to
That one is out of my wheel house unfortunately, hopefully @DavidDarnes can help with that question.
Just want to mention that Members in Ghost is in beta, and ergo still in development.
However you could utilise one of our Integrations to pass members to another platform that can handle multiple lists?
https://ghost.org/integrations/members/
Is there a plan to add the ability to send newsletters to members based on label in the future? @DavidDarnes
You’re probably better off using the Mailchimp integration so you can manage multiple lists: