Add "Sku" field to item list in quotes module

[dodom2]

Hello. I own the sales pack and need to figure out how to display a auto generate number field on the product list on the invoice. (https://prnt.sc/rgjt44) I would like to do via formula. Any suggestions on how to accomplish this? So for example when I create a invoice it would automatically take the "Sku" number from each product on the invoice list and add the sku number field of each item to the item sku field

[espcrm]

Currently the foreign field only show one item I believe. You can do it with the "List" formula from documentations but don't know how to. But I thought product code/SKU is quite normal, I expect it to be part of the Extensions already.

[dodom2]

Its part of it but its just not displaying in the product list which is what Im looking for. This way I can see the sku, product name, qt ordered, price and line total of each item.