tartan advice for relatives

[JohnnyO]

From c1830 onwards, Wilsons and other manufacturers were selling clan tartans widely across the world as fashion patterns and this practice continues to this day. A retailer will happily sell almost anything to anyone, they don't ask for proof of ID, if they did the tartan industry would have died a longt ime ago. If they like MacDonald, let them wear it, just make sure to educate them on what they are wearing.

Exactly what Figheadair says above. When I got my first adult kilt some 40 years ago the kiltmaker, Jimmie Kirpatrick of Thistle Bagpipes, Luss, said almost the same to me.
His other suggestions included, "Tell them it's a private family matter"; "Say your granny wore it"; and if it really bothers you contact the Clan Chief or Society and ask permission.
Whilst I did obtain permission from the Earl of Caithness to wear Sinclair tartan, in the intervening decades I've often been asked what tartan I wear, but never, ever what right I have to wear it.
Get the young ladies their tartan and I hope they thoroughly enjoy the wearing of it.

Bring Forrit the Tartan.