Suggestion on how to add child records based on a record value associated with another object

Does anyone have a suggestion on how to create a lookup in order to create new records?

My use case is as such: Purchase Order system application. However, I want the ordering party to be able to choose a "package" consisting of two choices - System & Size. Once they've chosen this 'package,' I would like to look up the system-size combo and insert all the line items associated with this combo record. Ideally, I envisioned a table with unique identifier (system-size), product model, type, cost.

Then when the ordering party selected the combo (system-size), we could look up all products matching the combo and add them to the order record's line items (children).

The closest I've come without using javascript or api calls is to create record rules for EVERY possible combo and add each line item (up to 4 line items per combo currently). This has already created over 100 record rules for the intitial setup. I cannot imagine how fun it will be to maintain down the road.

Any thoughts out there?

Thank you so much for your input!

To clarify - once the user selects 'System' and 'Size' options (maybe they're connected objects?) you want to present the user with a list of products that match to choose from?

If that's correct then would a search form with those fields work?

Another way might be to present a table or list view that's filtered for System & Size in JavaScript?