To capture customer # while creating using transaction XD01

Hello..Requirement is to capture 'Sold-To' customer # which gets generated internally by SAP. I tried exit 'EXIT_SAPMF02D_001' but not successful. I am using transaction 'XD01' to create 'Sold-to' customer and I need to capture internally generated customer # before KNA1 gets updated.

PLEASE ADVISE!.

THANKING YOU IN ADVANCE!.

FELLOW ABAPER.