Dynamic SAP BPC 10 member formula

Hi experts,

I'm using a hierarchy in a dimension and I need to aggregate members data using other functions than a simple Sum. For example :

Dimension X with the following structure :

PARENT

    Parent 1

       Member 1

       Member 2

    Parent 2

       Member 3

       Member 4

Dimension Measures that contains members like:

KPI1

KPI2

KPI3

The functions used to calculate KPIs for each parent in the dimension X change. Which means :

Parent1 = Function1 (Member 1, Member 2) for KPI1

Parent1 = Function2 (Member 1, Member 2) for KPI2

We can also find that KPI1 = FUNCTION (KPI1, KPI2)

How can this be achieved ?

Thanks

Maha