SLA to change Gain/Loss account when applying prepayment to standard invoice with different rate

Hello Expert,

Customer request the following:
When a prepayment in a foreign currency is applied to a standard invoice, and the two transactions have different conversion rates, the resulting realized gain/loss should post to the item expense account as in the standard invoice — not to the default Gain/Loss account configured in Payables Common Options.

Example scenario:

• Ledger currency: EGP
• Prepayment: 100 USD @ rate 55
• Standard Invoice: 1000 USD @ rate 50

Current accounting behavior:

Prepayment creation and payment

Event	Account	USD DR	USD CR	EGP DR	EGP CR
Create Prepayment	Prepaid	100		5,500
Create Prepayment	Liability		100		5,500
Pay Prepayment	Liability	100		5,500
Pay Prepayment	Cash		100		5,500

Standard invoice accounting