adjusting Gain Loss Accounts in SLA for On Account Credits

My client has a requirement to use different Realised Gain and Loss Accounts depending on whether it concerns Interco or Trade Payables or Receivables.

I am using the Supplier Type and Customer Type (Regular/Internal) as source value to drive the Accounting.

Made an Account Derivation Rule to populate the correct GL Account based on what the Customer Type is.

For Receipts and for Applied Credit memo's this works fine.

For On Account Credits - which you apply via the Credit Memo - Application Form, this seems to be working differently.

Standard Functionality works as follows:

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