I agree with you Alphabetical seems the most sensible and the easiest to follow and implement As to Mischa Barton I m not familair with her but I gather from the article that she was born in the UK to an English father and Irish mother and moved the US when she was four You mentioned naturalized US citizen but I don t see that in the article Is she a US citizen If she is active in the Irish American community or plays up the Irish part of her heritage then I d say yes otherwise I d say no 50 Irish heritage is enough to make her Irish American in the conversational sense of the word but not enough to bother tagging her with the category IMO