Thank you so very much for taking the time to post such a detailed response, especially the information on the relationships of the coats of arms and motto.
Thank you to everyone who has replied off-forum suggesting that I contact Alexander (Sandy) Stewart of the Stewart Society. I have done so.
In the year since I posted this inquiry I have managed to learn much. Perhaps I should update my initial inquiry:
The origins of the Ardvorlichs is known and my research can be found here:http://www.chuckspeed.com/balquhidder/balquhidder%20stewarts...
I have managed to link my earliest directly connected ancestor, Robert Stewart (b.1775) of St. Fillans, Comrie, Perthshire to his ancestor, John Dhu Mohr Stewart (b.ca.1630) of Dalveich, Lochearnside, Balquhidder, Perthshire. John Dhu Mohr was the illegitimate son of Major James Beag Stewart, 2nd Ardvorlich (who murdered Lord Kilpont). John Dhu Mohr was chief of a clan in Dalveich, which is just across Lochearn from Ardvorlich.
The relationship between John Dhu Mohr Stewart and his descendant, Robert Stewart of St. Fillans, is demonstrable, however the direct line has not yet been proven, so my search has now narrowed to the Stewarts of Dalveich.
Does anyone have knowledge of, or is anyone else researching, the Stewarts of Dalveich, Lochearnside, Balquhidder, Perthshire, Scotland during the 17th and early 18th centuries?
Hamilton, Ontario, Canada