How best do I create a Proforma scenario in FCCS?

Summary

A client wishes to have an "adjusted" Actual scenario that adds historical data from acquisitions

Content

Since we would be entering new data into the past, this would require unlocking and changing closed periods if done within the Actual scenario, so the first conclusion would be to have another scenario.  How do I best blend in the locked reported figures with adjustments to these that can be changed whenever, while always be up to date with the Actuals?

1. Can we add scenarios together? Actual + Proforma = Actual incl. Proforma?
2. Can we script a copy of scenario to scenario as an On Demand Rule? ex DATACOPY Actual->Total Input and Adjusted TO Proforma->Other Data;