Forecast Transfer issue

Hi,

We are trying to tranfer forecast of Product 'A' in Location 'X' on to Location 'Y'. We ahcieved the functionality through a BADI. Now the issue is, If the forecast exists for Product 'A' in Location 'Y', it is getting over written by transferred forecast from Location 'X'. We would like to get the sum of forecast in both the locations for the product as the total forecast in location 'Y'.

Could you please suggest how to achieve the functionality.

Thanks,

Krishna