customer needs to change the COA and will create new LE, how to handle the current working Proc BU

Summary:
In case customer have one legal entity, one procurement BU and for some financial issues, he needs to change COA and will create new legal entity and ledge, reimplementing the financials modules, can we retain the Procurement BU to continue work with the new ledger, what's the best approach to follow so the procurement team not being affected with the changes and didn't lose the historical data on the current BU, considering there are a lot of open PO's and transactions they need to work on.

the options we thought about:

1. is it applicable to retain the current Procurement BU with all data and update the ledger and legal entity from assign business unit business function task (will it work if we considered reconfiguring the TAB/SLA to map the new COA?)