advice regarding changing the Fiscal Year

Hi Bpc Friends

I would like to have some advices regarding the implications of changing the FY.

At the moment our fiscal year run from May to Apr but we would like to change it to run from Aug to Jul so we will face the scenario to have a fiscal year of 15 months in the middle of the changing process.

Our application is YTD but we need to have periodic reports. This means we need a more complex formula for YTD to Periodic to be able to use May as first month for some years and August as first month for other years. is that possible?

Thanks

Michele