When you are on the Candidates tab in the External Exams Manager module, you can tick a box so that you can view the examination arrangements for former pupils. However, if you want to enter an arrangement for a former pupil who is now returning for exams, there is no way to enter that via this screen, even if you have selected the Former Pupils tick box: the drop-down list of pupils allowing to you add a new arrangement only lists current pupils.
It would be great if arrangements could be set for all candidates, not just current ones.