The following diagram shows how multisite support for targeted content is structured.
Areas appear underneath /content/campaigns/<brand> and by default each brand has a master area, which is created automatically. Each area contains its own set of activities, experiences, and offers.
To look up targeted content, the pages or sites can map to an area. If there is no area configured, AEM falls back to the master area for this specific brand.
The following diagram is an example of how the logic works for three sites, called site1, site2, and site3.