unplanned delivery cost booking

hi,

i need to clarify the scenario of booking the unplanned delivery cost.

1) we book unplanned delivery cost during MIRO because in PO there is no condition category B,F (freight/custom condition type) maintained. possible is during PO still not agree by both party on the freight/custom cost.

until invoice, vendor invoice has an additional line for this freight/custom cost. so we need to capture it in unplanned delivery cost. correct?

2) although planned delivery cost (meaning freight/customs condition type maintained in PO) exist, during MIRO, i have to choose the planned delivery cost indicator to set off the freight clearing account.

now when receive invoice, vendor has additional line to have more delivery cost, so this additonal delivery cost i have to book in unplanned delivery cost?

thanks