These are initially unrelated activities that have been created and linked together as multiple activities to express one event. You can even use a function key specifically for related groups of activities to view them on a single screen display. A good example of a related activity set is an initial call to a customer who is at lunch. You record the call with a note that they were unavailable because they were at lunch, once you complete that activity, you create a new related activity for another phone call. You get a chance to make that call only to find out that the customer is in a 1 hour meeting which occurs everyday at the same time and therefore can't be contacted until later in the day. You also complete that activity and create another related activity for a third try to your customer. On that try to connect and have a great conversation. You mention that you called previously and agree on a good contact time to conduct business. In the future you will retain the information in these three phone calls with their result on the contact record. You will easily see that a phone call at a certain time will fail because the customer is either at lunch at that time or in a daily meeting.