Creating several records pr. row in a layout

Question

We are building a BPS solution on an existing BW implementation. In the BPS solution the users will enter adjustments to the data already existing in a BW cube. The adjustments will be stored in a new transactional cube, while keeping the old BW cube.
Our problem is this: We will need to create several records for each row in the layout(s). For example, all entered records should automatically be reversed in the next period.
How can we create additional records? Is an Exit function (ABAP) the only option?

Answer 1

By "automatically reversed" I mean that the amount (the most important, but not the only, key figure) will be negated. That is not possible with a copy function.
But the problem is even more complicated. 'Activity' is a characteristic. Based on an entered record we will need to create one or more derived records with a different activity, but with the activity will be based on the activity of the original record. In some cases we will also need to make calculations on the amount of such derived records.
And both the original record and the derived records will need to be reversed in the next period, i.e. negated amount and period change, which will again double the number of records to write per row in the layout.
The copy function can't both change Activity AND use the Activity of the original record as a condition.
But if we find a way to use the copy function, we would still need to use a FOX formula for changing the amounts (and also some other key figures as well) when necessary. Planning sequences are linear, so I assume it could be difficult for a planning function to execute for several records derived in an earlier step in the same planning sequence.
We have decided to look deeper into the FOX programming language and see if it's flexible enough to solve all of these tasks.