Adding SKU or family to invoice table

This was asked elsewhere but did not get answered.
I need to show ‘family_name’ on the left of the invoice item table for the book keeper to register the invoice correctly (I figured out SKU but fail for family_name so far).

When I lest all ‘$item’ fields with

<?php print_r($item); ?>

I see ‘family_id’ but not 'family_name’
How can I add a model to obtain the name from the related table ‘families’?
I guess I need to add to ‘pdh_helper.php’ in a ‘for $item in $items’ loop but how and where?

Any help would be very welcome

A post was merged into an existing topic: Adding Product family in quote