How to create an editable grid from a record

Hi! I have a doubt with the approach of my application and I would like to know your thoughts!

In my case, I have a summary view of PO in which I have a read-only grid with the PO lines.

I created a related record action to "recepit" the PO Lines ("Recepcionar Pedido", which will link to a process model), and now I want to create an interface with the following conditions:

• 1) I must show the same information/table with the PO Lines (I just need some of the fields). Not need to add new rows
• 2) I must be able to create an extra-column to introduce manually 

In order to do this, I thought several options:

• 1) Create an editable grid based on the data of a record (like a read-only grid, same values, but with the posibility to manipulate it)
• 2) Convert the read-only grid in an editable grid (i dont know if its possible or complex, I know the configuration are totally different)

How can I manage to do it? If it´s not a good approach, I would like to hear from your recommendations 

Thanks a lot, any idea would be useful