Upon BU selection, system must default the Segment 1 value at invoice line account combination

The system must automatically default the Segment 1 value in the invoice distribution account combination based on the Business Unit selected at the invoice header level. While this can be achieved through Subledger Accounting (SLA) rules, those rules only apply during the Create Accounting process and will override values at that stage. However, the requirement is to have the Segment 1 value defaulted before accounting, i.e., at the time of invoice entry or distribution creation.