Old attendance information (other than general info transferred, eg the percentages across the previous years) is not required for a new school. You do not have a day bay day / lesson by lesson breakdown when they come up from Primary.
You need to remember that this is a new school. If a student has a history of persistent absence it will already be noted and you do not need this at the new school. The old data will be retained by the LA in either their central systems anyway, or they may hold an archive of the system for a period of time, but the old server and the data base on it is to be securely wiped to meet the DPA.
If your Academy wants attendance to be an exception then this should be discussed with the LA and the project managers involved.