Creating several records pr. row in a layout

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?