Hyperion Planning - copy data from 2 entities into 1 new entity

Hello. We are running Hyperion
Planning 11.1.1.3. In one of the applications there has been a request to setup
a new region/entity (C). This region is to be the consolidated total of 2
existing entities, A and B. How can I add the data from both of these entities
into the 1 new entity?

I'm familiar with copying data from
one entity to another using the DATACOPY command through a calc script. I would
like to use this process because it is very fast, but I don't know if it would
work correctly. I'm not sure how to add data from 2 regions and load into 1.