Well, but there was historically a third captain of recruits, too! Captain John Sweetenham marched from Ruthven Barracks towards Fort William two days before Scott, with another company of reinforcements. They were captured by the MacDonells as well (the first skirmish of the war) and both Sweetenham and his men were brought along and witnessed the raising of the standard at Glenfinnan, like Keith and his recruits. Sweetenham was later paroled and made his way back to Edinburgh and then London (I suppose he promised not to take part in the war).

Sweetenham was actually the one who, on his way back, warned Cope not to go over the Corryarrick, which pleases me, because it means that when Keith fails to escape at Fassefern in my current AU, the battle at the Corryarrick is not actually a separate AU branching point. : D (Although to be quite accurate, Cope was also warned by Duncan Forbes.)

I think Keith is an amalgam of Sweetenham and Thomson.