I am a Young on my mother's side, so I wear (well actually not yet, as im saving to have a kilt made in Young Weathered) my clan tartan.

Clan Young was/is a sept of Clan Douglas, so I can also wear the Douglas tartan (my next SWK purchase)

Checking my family's genealogy, I suspect there may be a MacKay and a MacKinnon link here and there, so I could wear those tartans as well (but I doubt it as it would be a stretch)

And finally, Clan Young's lands, castles and peel towers were inside what is now Roxburgh District so I could technically wear that tartan as well.

I've read somewhere that technically all scots can wear the Stewart tartan because since the Clan Chief was also the king/queen of Scotland, all subjects were also clansmen by definition.

Is that about all 'family' and 'entitlement' tartan wear options without going into the universal tartans? (black watch, pride of scotland, etc.)