Copy values from billing plan to Invoice without revaluating

Hi,

we want to copy values from the billing plan in the sales order to the invoice exactly as is without any changes.

In the sales order we have a billing plan. The values in the billing plan are calculated using an user exit. During invoicing the values are copied to the invoice and revalued, using SAP standard. The values in the invoice then differ from the values in the billing plan, which is wrong.

We use pricing type "G - Copy pricing elements unchanged and redetermine taxes". But according to note 24832 the values in the invoices are ALWAYS revalued. This is exactly what happens.

Is there any way to do this in standard or via a new pricing type (customer reserve X)? I tried a calculation rule in the pricing procedure but it is tricky to catch all scenarios, especially because SAP is super eager to revaluate the invoice values constantly.

Thanks for any help!

Best regards