Change Tax Code in line item while uploading Purchase Order

Hi everyone and thanks in advance for your help!

Is there a way to change Tax Code in a line item in MIRO before upload a Purchase Order?

I mean, I go to MIRO transaction and select Purchase Order/Scheduling Agreenment, write the PO number and press ENTER, before the line items are uploaded, I would like to change the Tax Code in some of the lines. Is there a way to do that?

Thanks!