Advice on when to archive data that is never really "retired"

My customer has a requirement to change and reprocess old data. I would appreciate some advice on archiving strategy.

One example is agreements in SAP CRM, where up to 10 years old agreements may be changed and this should generate new invoices. On one hand, there is a very large number of agreements (~500.000 agreements created each year), but only a fraction of the agreements need to be accessed and reprocessed more than a few (say 5) years back --> I.e. archiving and deletion of 5+ years old data from the SAP online database seems logical.

On the other hand, the small fraction of 5+ years old data that needs reprocessing still translates to quite high numbers in absolute terms, say in the order of a few thousand agreements per year. This number is high enough for the business to require fully automatic reprocessing capabilities, i.e. changing the old agreements should trigger the same process flows as changing current agreements, invoices should be automatically generated etc...

As a matter of fact, there are also requirements to retain other data (e.g. business partner data) for indefinitely (50+ years) and allow allow changing this data while these changes will/should trigger business processes (that are implmemented in the SAP system) for performing recalculations etc...

I know that with the SAP ADK/ArchiveLink arhiving solution, SAP strongly recommends against reloading archived data into the database for reprocessing, unless the reload takes place immediately after the archiving step.

My question is: With these kind of customer requirements in mind, is it worth to even consider SAPs archiving solution ADK/ArchiveLink and implement some kind of reload strategy? Or is it a definite no-no to do this, and instead fight back all requirements to reprocess old/archived data automatically (i.e. only consider to READ archived data and e.g. manually re-create archived data as NEW objects in the SAP system)?

Are there any other "archiving" solutions that should be considered, other than using ADK/ArchiveLink, that would better fulfill these kind of requirements?

I feel this should be a relatively common requirement these days to be forced to retain data for a long time and also be obligated to change this data, at the same time as performance and offloading the online database is necessary. But I can't find any documentation or advice from SAP about how to normally handle this situation.

Can someone advise on this please?

Thanks,

Lars