Which family tartan

[gilmore]

Forgive my ignorance, but regarding clans... are there websites (for example) associated with each which would be considered "official"...?

Yes. Many of the chiefs of clans and chieftans of septs have their own websites (though not all do by any means) which I guess could be called official as to that person.

There may be several associations for each clan with their own websites, usually distributed geographically. E.g., a _________ Clan Associatoin of North America, _____ Clan Association of Australia, and so on. I guess those are official as to that clan association.

Clan associations are of course groups of people who descend from a clan and were formed by and governed by them. I think it would be accurate to say that the chief of a clan, or chieftan of a sept, are the final arbiters of most matters involving the clan directly.

If you Google, you can probably find the one(s) you are interested in. If not, post a request for info here. There are quite a few knowledgeable folk here.