If you have a rejoiner you need to create a new employee record so you are duplicating data. There is also no easy way to copy across their personal information or to look at consolidated reports as their data sits in two separate employees.
It would be great to find a leaver, make them a rejoiner and then review their previous info and update as required. If they haven't had a job since you can then carry across all the data from their P45.
Thanks for your suggestion.
This is now under review and we will update on its progress.