Yeah, and I am a member of one of those other cultures. I maintain my position that you are talking about an overblown problem. And if it becomes a problem, they can pick a fourth name to distinguish it. Immigrants making modifications to their names when they arrive in a new country is not a new phenomenon, and the overwhelming majority of them will not have to make any modifications as well.

Here's a better attack line for you to adopt, since your previous one was bad: How would the proposed system deal with people who had non-unique names before the system was implemented? That is something that would be far more disruptive.