My #perl is very rusty (and this isn't my day job), but I found your #GeneticGenealogy project very interesting, so I wrote a #phython script that does what you ask, loops through two files, and if both first and second fields match, then the text is appended. Is your project related to a surname group at #FTDNA? I'm starting as a surname project leader there (#LittleFamily). I love playing with #regex puzzles, so it was fun to apply it to #DNA.
Best! Steve
#genealogy #Geneadons