{UserID,
 UserName,
 UserPhone, // primary key
 Option1,
 Option2,
 Subscribers: [{SubscriberID,
                SubscribersPhone, // secondary index
                SubsciberOption1,
                SubsciberOption2
               },
               {SubscriberID,
                SubscribersPhone, // secondary index
                SubsciberOption1,
                SubsciberOption2
               },
               ...
              ]
}