Add new members to an existing audience.

Each member object must include a key matching the audience's phoneNumberColumnName. If it's missing, the API returns 400: "Each member must have a <phoneNumberColumnName> field". Adding members that would exceed the audience limit also returns 400.

Note: if the audience belongs to a different organization, the API returns 404 (not 403).

{
  "members": [
    {
      "phoneNumber": "+1234567890",
      "name": "John Doe",
      "email": "john@example.com"
    }
  ]
}

{
  "status": true,
  "data": [
    {
      "message": "5 members added successfully",
      "data": {
        "added": 5,
        "skipped": 2
      }
    }
  ]
}