Business rule for Planning Calculation

Hi,

I’m writing a custom calculate business rule for an Account which is planned like this - Look at the same intersections 12 months prior and see if there is data. If there is, use that value to set the value for current time period. If there is no data in that intersection 12 months ago, look for a value 24 months ago.

I need to do this for just 1 account but different UD1 and UD2 intersections.

I tried to use GetDataBufferUsingFormula and thought of looping through all intersections but DataBuffers give only those intersections where there is data.

How should I go about this?