HCM Extract changes only with different parameter

Hi

We have are requirement to create a changes only extract with legal entity parameter, so that customer will first load the data into 3rd party system for one legal entity LE1 and then continue to load the changes only detail for the same LE1 for some time (lets say 3 months), after 3 months customer will use other legal entity LE2 to load full data and continue to load changes for LE1+LE2..so on. How we can do this requirement in changes only extract , I think we need to use LE parameter, but how changes only works if I change