There are more threads on here than I can count that touch on the fact that tartans of different clans shouldn't be mixed. It is further held that one shouldn't mix unrelated tartans (eg; two universal tartans such as freedom/Gold bros. and Scottish heritage). It was also once questioned if one could mix a clan tartan with a non-clan. The general opinion was that it should be avoided.

My question is about related tartans. Specifically, could one in theory wear two tartans of the same clan, organization, &c? Some examples would be a Salvation Army kilt with a Salvation Army Hunting fly plaid, a Royal Stewart kilt with a Black Stewart waist coat, a Ferguson Red kilt with Ferguson Old flashes, or a Clergy #2 (with the green stripes) tie with a Clergy Grey kilt and a Clergy Corporate waist coat.

Then, what of the various color pallets such as modern with weathered and such?

Bear in mind that this opens up the possibility of many horrific combinations. I ask out of curiosity, not the intent to try it.