Populating a record type with multiple rows at once

I'm new to Appian. I have a user main page, and the user is able to click on a icon within the read-only grid, which is a recordactionlink, launching the interface to carry out managing of user information. Now, it would be simple if it was just the user I am handling.

Considering that this action is within the "Users" Record Type as a related action, I was planning to also use this same interface to do management of another record type "Access" within the same interface. My issue is with the Access of course.

With it being a grid/gridcolumn layout, with 3 columns, Location/Department/Role, the user is only able to populate the Access Record Type, 1 row per Location. Basically, the User Record Type and the Access Record Type has a one-to-many relationship. In an attempt to control the amount of rows the user is allowed to create within this interface, I first used a!for each to loop through the location Record Type, which basically ensures there's only as many rows as there is locations.

And within each row, I have Department/Role, which both firstly loops through the Access Record Type, filtering based on the fields of UserID (saved when selecting from the main page), and LocationID (contained in a local variable within each iteration. This helped me dynamically display data that already exists within the Access Record Type, displaying null for fields that don't exist.

Here is the main issue. How do I get the ever-changing (due to both Department and Role being dropdowns accessible at all times) data from each iteration to be saved into a singular rule input, which I will be trying to send into the Access Record Type as separate rows, through a process model?