Need help with Importing TXT file and inserting into Variables Print Merge


I'm really hoping someone can help me.

I am engraving pet tags and each tag has different names on them. I have tag jig files made up that have each pet tag shape and inside each tag has variable lines eg : <tag16line1> please see image.
I also have TXT files that has the details (pets names) that need to be imported into the variable lines of each tag in the jig file (image attached).  I have no idea how to import them into this file. Hoping someone can please help me?