How to use a text field for data entry in a subtable. I scan box that auto-populate new rows? Can I make a scan window auto populate fields within existing rows rows?

I work at a company that has a revolving serialized inventory of the same items going in and out for “jobs”. Often times it“s the same kinds of items going out. 
i.e. (1) Camera, (2) batteries, (2) memory cards

We”ve identified each of our items with a “serial number” and can auto populate a row in a subtable by filling it in. 

So I have made a template “kits” table by listing a rows of items in a “gear” subtable without info in the “serial numbers” field. I can then copy those templates over by selecting one of the templates as an option in my “jobs” table.

To make this process more user friendly we“ve added barcodes to our items to scan in. Can I use a  text field to fill in the ”serial numbers“ field for their respective items from ”kits“ table? How?