Automation to map based on range of number

Hi,
I have a question in regards to setting up an automation to create and map record into a many-to-many relationship joint table.
There are three tables in this case:
1. Handhole-to-Handhole Table (This is a pre-define table, where each record has been identified a start and end stationing number)
2. Production Table (This is where the user enters his/her production everyday and identifying which stationing location the production is)
3. Many-to-Many joint between HH-to-HH and Production table

Ideally, what i'd like to do is when the user creates and/or modifies a report in production with the indication of the start and end stationing number. It automatically look up which Handhole-to-Handhole record(s) is/are related to and then snap it down into the many-to-many joint table.

I've scribbled up to show which production record show tie to which handhole-to-handhole record(s); however, I'm completely stuck at figuring out the automation to do it based on the "Start" and "End" range.

I'm wondering if anyone can provide some insight on how i should tackle this problem.

thanks :)