Currency Decimal Places - Urgent

Hi all of you..

When earlier stage in my project , client has not told us to change the decimal places in Foreign Currency - USD.

Now client is asking to change the decimal places for 4 digits..

( Earlier 2 decimals )

Now in Global settings t.code OY06 , we are trying to change for 4 decimals , but system is changing the entire existed transaction values regd USD as for 4 decimals , data inconsistency is coming.

Is there any procedure to change the decimal places from now onwards...

Or else is there any procedure to get 4 decimals in PO..

Plss help me it is very urgent to me ..we are trying to shoot from 10 days..

Thanks & Regards

Ramki