djct59 - I stumbled upon a text that references thirteen children of Rob Donn Calder -- the 44 page "Life of Rob Donn" by Hew Morrison that is part of his 1899 book Songs and Poems in the Gaelic Language by Rob Donn.
on page xxxi
In 1769, while at Saingo, his youngest son was baptized and named George. His family is stated to have consisted of thirteen, who "were mostly all spared to rise round him." Of these, eight -- five sons and three daughters -- are known to have attained manhood and womanhood, but little is known of some of them beyond that fact. His eldest son was James, who, in 1774, married Jean Stewart in Balnaceil. ... His second son, John, enlisted in Macleod's Highlanders and was killed in the Battle of Arnee in 1782. Hugh lived in Crosple for some time, Colin was in employment about Balnaceil, and George is not mentioned in the record after his baptism. His daughters were -- Isobel, married to John Mackay; Mary, married to Donald Mackay; and Christian, married (1) to Hugh Murray and (2) John Morrison.
Hew's narrative is a bit rambling. After a four page digression into the the surname debate Calder v Mackay, Hew returnes to Rob's kids and starts narrating baptism and marriage details from the Parish Register of Durness. This narration is limited to the eight Calders mentioned earlier in Hew's narrative (above). In this narrative Hew neglects to mention the Murchoch Down listed in the baptisms of the three daughters of Donald Calder a possible granddaughters of Rob Donn Calder, identified as "Murdoch Down's son" or as "alias macmhorachiedhuin" as discussed earlier in this thread.
Using keyword searches for Donn, Doun, Down, Dhuin, Duin, and Calder I found 42 baptisms in PRD, starting with "Hugh Calder, alias Down, in Balamhulich, christened Mary - 31 Mar 1765" and ending with "Alexander Morison, alias macuilam macrory, volunteer, late in Cerrauc, now in Ardaloch, and his wife Lucie Mackay, daur. of John Mackay and Isobel Doun, George - 30 June 1804."
This week I ordered the Ian Grimble book to see what he says.