Portal selection by hierarchical list.
I began with the Invoices starter solution and have added a couple of fields to my product catalog: category and sub-category. Both hold values from simple value lists, using custom values. I populated those fields in every product record.
In the invoices layout, where it contains a portal into the line-items table, instead of a simple list of all products, I want to present a hierarchical menu - organized by category, sub-category and product - so that the data-entry user will see items in the same order they are presented in the catalog.
At this point, it became abundantly clear that my education on relationships, at least, has huge gaps. Can anyone suggest ways to proceed?