Ask HN: How to create follow-ups in Google Calendar

I have a problem that I am sure faced by many. We are not able to complete many tasks in a single To-Do posting. Like talking to someone to fix up meeting or paying bills. To manage such things, there are many follow-up To-Dos required. When you call someone, he is busy. So, a follow-up is to call in an hour. I have not seen such a minor but extremely important feature in any popular calendar app such as Gcal (popular to me - 'cos I use it). I want to click on an even in gcal. It shows a button for a follow-up. I click it to book another calendar event. These follow-ups become a task ring so that, I can understand how much total time was lost in setting up a trivial meeting. It would be awesome to use follow-ups for booking sales orders. Such a task ring will tell me how much time is required to actually close a sales call and grab an order. If I am able to hook it to customer (contacts) it is even better - I can bunch a few contacts that are fast / slow for purchases and give them the right treatment as per their history. Someone knows how it can be done on Google Calendar?