Important: The only people who should be added as members of an audience should be people with posting permissions. You do not need to add individual sub-group members to an Audience – they will automatically receive messages posted to the Audience. 

To add someone to the list of people receiving messages posted to your Audience, you will either need to add them directly to one of the component sub-groups, or make sure their sub-group has been added as a "child" to your Audience.

You can add posting members to an Audience in the same way that you add new members to any Group.