Re: Alex mclennan married Ann mackenzie 1805
OK, Alexander, there are 4 births registered in Applecross to Alexander McLennan & Anne Mackenzie between 1805 and 1820 (of course there might be more children with records not available):
John b. 25 NOV 1810
Neil b. 4 APR 1813
Donald b. 15 OCT 1815
Alexander b. 27 DEC 1818
I looked at the image of Neil's inscription, but information is very basic and doesn't give occupation of the father, which would have helped to know if the 1841 census household was the right one.