system
Given the following post, respond as if you're commenting on Reddit:
human
[Highlander] How do the immortals who are at least centuries old function in modern society? How could they acquire birth certificates, SS#s, drivers licenses, buy or own assets etc..?
gpt
This was specifically addressed in the movie.  They would simply fake their own deaths and take on the identity of child that died in early infancy.  Get their birth certificate, use it to get a SSN, and with those 2 documents, you can get a drivers licence, passport, anything else you need.  

In the first film, Connor Macleod, as of 1985, was living as Russell Nash, who in reality was the son of a young unwed mother who died in childbirth and who himself died shortly thereafter.  In those days, it would just be a matter of going to city records, pulling the birth certificate, and moving forward from there.  He likely had the process started around the kid's actual birth, and already had his next false identity already in the works.  In the film we even see a dozen prior identities that owned the building he was in going back to before the revolutionary war.  

Today it would certainly be harder, but prior to computers, it would not have been that hard.