Steps:

• Create a list of events ( example daily)
• Choose a day in the middle of series, which to make some event already happened. Edit it and make the series of even not repeat any more/ repeat weakly
  Error:
• It edit all events in series, including the one that already happen in the past. That is wrong
  Solution:
• Like google calendar, everytime you edit event in series, you will have to show the pop up with multiple option for end user to select to apply