manaia: I understand that you have to have either a booking or a series link programme in the planner to keep the series link alive. If the series has finished then there will be no booking so the only way to keep the series link alive would be to keep one of the programmes in the series. If you do this and another programme turns up with the same series ID then it will be booked. Unless you get a box with another person's programmes or bookings actually showing in the planner I don't see that you would be able to pick up their links, so this seems unlikely.
I am sure that is not the case. I had no bookings showing for Darren Brown, JAG or Monk, and no recorded programs of them either. Bookings then showed up out of the blue. In all three cases, I had series link on the whole time. During the two or three week hiatus for JAG and Monk, for example, there was no advance booking, and I had watched and deleted all recorded copies of them.
I do believe you are correct. I haven't had time to test it out for myself though. I originally thought that series links were automagically managed in the background. Then I was told (authoritatively I thought) that you had to have an entry in the planner to keep the linking alive (a booking or the last recorded show). This would not be as good if it were true. Thanks for putting me right.