Hierarchy key figure rollups in BPC 10.1 BW 7.4

Hi All,

Is it possible to create key figure rollups in BPC 10.1 unified or BW 7.4. We are on BPC 10.1 unified on BW 7.4 and need key figure hierarchies that can be based on a formula (example = top node = Node 1+ Node 2 - Node 3). We understand that we can build "formulas " to achieve this in BEx query or do all calculations in cube. However, we are trying to find if their is a way to build a hierarchy/rollup such that it will take care of the addition/subtraction of underlying nodes to produce top level result.

Please advise. We are implementing planning and reporting functionality using BPC 10.1 unified.

Thanks,

Anya