How to customize Realized Gain/ Loss Account in Payment Accounting- Case Study

Business Problem:

During each period close phase, when is business performing revaluation, then Oracle Fusion parks 'Unrealized gain/ loss amount' into different- different account as per set up under Revaluation definition (Manage Revaluations page) but when business is doing settlement of the vendor liability balance due, then system records 'Realized gain/ loss amount' into accounts setup under common options (Currency Conversion section under Manage Common Options for Payables and Procurement page). Payment accounting is happening both at the time of issue and clearing for that BU. Technically system is not allowing to differentiate Realized Gain/ Loss account except by changing at BU level.