Hi
You don't need any implicit enhancement in order to update account document while creating the bill: you can use the exit EXIT_SAPLV60B_008:
here you can insert your value in structure ACCIT-SGTXT
The problem is in VF02: because the fm of interface with FI is not called again so the exit above shouldn't be triggered..
In this case you probably need an anhancement place where the bill is saved
Max
