Trying to get this working using the TS definitions, how can I have multiple subject sets underneath something in the TS def?

Use the

related

object to create relations that hold your subject sets. If you need more than one on a give relation you can use

|

to separate them so something like this:

// UserGroup represents teams, departments, or role groups
class UserGroup implements Namespace {
  related: {
    // Members can be Users OR other UserGroups (nested groups)
    members: (User | UserGroup)[]
  }
}

Thanks