MIRO - Unplanned delivery cost to impact material MAP and specific GL account

Dear all,

We have the following business case for which we didn't find any solution yet.

We purchase materials valuated at moving average price (MAP) through purchase orders.

It happens that not freight costs when planned for a PO then no freight condition entered. But sometime, after the goods receipt we receive a freight invoice that we want to post against the PO to impact the material MAP and a freight GL account.

What we tried:

When we enter invoice in MIRO we recall only PO lines related to the material purchases, no freight line (because no accruals planned). Then if we use the unplanned delivery costs field it will impact the MAP but not the right GL account (Goods purchase account instead of a freight account).

If we change the customizing of Unplanned delivery costs field to post into a separate freight GL account then the material MAP is not impacted by those costs.

If we use the GL accounts tab in MIRO we will only post to GL account but not impact the MAP.

Do you have any idea on how to process that in SAP?

Thanks a lot.