Forecasting using inflation rates

Hi

I have a requirement to generate the forecast by applying inflation rates. Planning will be done on rolling 24 months and then these should be projected to long terms plan (5 year rolling) based on inflation rates.

My initial thought is using script logic copy the 24 months forecast to remaining 36 months and then multiply with the inflation rates. But this calculation is not very straight forward, because rate should be applied to value in previous periods.

For example

Can you please share your thoughts ?

Version is

BPC 10.1 Standard

Thank you very much.

Sincerely,

Ram