Say you have these tables:
parent::ParentID = Child::ParentID
On a layout based on Parent, you have a portal to Child with these values listed in different portal rows in a field named Fruit: Apple, Orange, Kiwi.
Then a calculation field defined in Parent as List ( Child::Fruit ) will return the list:
A script step executed from the same record in the Parent layout that uses this expression will also return this list.
It works. Awesome. Thank you so much.