1

From any document where a INV.in can be generated (PO & PO/R), right click on a row item to display the contextual menu:

Select "INV.in . Invoice/from provider", then "Generate the document":

2

The INV.in sub-module is highlighted to show that it is holding changes waiting to be validated:

Click on it.

Important: You can repeat the same procedure from step 1 with other row items to be added to the same INV.in

3

Review the preset fields value and enter the missing data, then

validate