Copying values from one scenario into another

Content

For forecast scenarios, we require actual values of the the previous months of the year. Copying these values in HFM was very easy and also performant.
When we create this function in FCCS in the business rules, FCCS takes an extremely long time to copy.

I think this is because a) we are not allowed to use the copydata command, b) we have to use IF-statements on sparse dimensions to restrict the scenario and entity dimension and c) the accounts on the dense dimension have to be restricted by fixed statements.

Does anyone already have experience with this?