purging secondary ledger

A client site had Secondary Ledger available for some time. Meaning : they activated, and also de-activated this feature, all some time ago.

Now, we are looking aty purging GL data, using the standard purging tools.

It's pretty clear that some setup needs to be changed again, to achieve the following:

When purging the corresponding Primary Ledger, it would be easy if the Secondary Ledger data would be purged as well.

Question is : is it the case ? Is it done in the background ?

Or, do Secondary Ledgeres need to be addressed implicitally ? I didn't have any Secondary Ledger listed in the LOV that allows me to clean Ledgers in the Archive and Purge screen.