Updating non-logical OTBI to Logical SQL OTBI without rebuilding?

Summary

Updating non-logical OTBI to Logical SQL OTBI without rebuilding the original OTBI?

Content

I need to update an existing OTBI (non-Logical SQL) to use Logical SQL and finding out how to do this without rebuilding the whole OTBI from scratch is quite a challange.

My analysis to update just contains "Payables Invoices - Transactions Real Time" SA and my change is to include the {check date} from "Payables Payments - Disbursements Real Time". Using a join between the 2 subject areas would yield only paid invoices and I need to pick up Paid and Unpaid invoices and hence the need for an outer join between the subject areas and hence Logical SQL.