Are you trying to connect Archibald McTavish, tacksman, Garthbeg, who died 23 Jan 1831 in his 76th year, to Donald McTavish b. 5 Nov 1800, whose baptism you suggest, in post #126, was witnessed by Captain William Fraser?
You may not be aware that the register for Boleskine, Inverness-shire, Scotland is quite fragmentary before 1796, and reads as though it was reconstructed after the fact by interviewing what families could still be found in the area.The Second Statistical Account of Scotland notes that the original pre-1796 register was dropped in a swiftly flowing stream and lost.The register at Fort Augustus was quite regularly kept, although it obviously does not contain all of the baptisms that took place in the district.From 1764 onwards, the name of the mother is given in most cases; before that, only the father’s.Sometimes the entries include witnesses to the baptisms, but usually not.These parish registers are frequently searched by descendants of expatriate Scots who emigrated in the late 1700s and early 1800s to Canada, Australia, New Zealand and elsewhere.[The Frasers of Stratherrick, including list of places mentioned in Boleskine and Dores Parish registers pre-1800 – Canadian Explorer, June 2000].
The McTavishes who settled in Stratherrick are considered to be a sept of Clan Fraser of Lovat.