Need ATP check through BOP in APO for orders with full confirm qty

Hi Experts,

     Need to run ATP through BOP in APO based on current availability in APO. How to set  this in APO.

More Clarity on requirement:

Sales order flown from ECC  is having confirm qty. But i wanted to check ATP again in APO based on APO stock and then assign new confirm qty.

I can able to filter orders with confirm qty in BOP using filter cliteria. But post BOP run, i am not getting any difference in confirm qty.

There is no change in the confirm qty given by BOP, seems no further ATP calculation over current confirm qty.

But need to know the setting using which BOP can reassign the new confirm qty for orders based on current availability in APO. All ATP setting is in place. I feel only some check is required in BOP paramters screen to do this.

REgards,

Ajit