How to copy data from an editable grid and add new columns

Hi! I´m trying to plan an approach for my application and I would like to hear your recommendations

In my case, I have a record of Purchase Orders (PO) and Purchase Order Lines (POL)

In my summary view for each PO, I can see the header data (PO) and the lines (POL) as it is shown in the image below:

Now, I would like to use a button to "receipt" the PO lines. A pop-up should appear, with the same purchase order lines (the table from the record POL), and I want an extra column for the user to write the quantity and do different checks.

I was thinking about using a related record action, connected to a process model with an user input task as the start form. The user input task should use an interface with an editable grid which has THE SAME VALUES of the PO lines (like, by default), and then I can add the new column in the interface

I don´t know if my approach is correct or if is there a better way to re-use the same read-only grid and transform it into a table with an extra column

Thanks in advance!