I've got census records for the following family in 1881, and three of them in 1891. In 1881 they're in Alyth, and in 1901 the whole family is in Cargill, but it would really help me to find them in 1891!
William Morrison b Aberdeenshire 1834
Janet Morrison nee Grant b Banffshire 1842
Their children -
Alexander b Alyth 1863
Jessie/Janet b Alyth 1865
William b Alyth 1866
James b Alyth 1872
Isabella b Alyth 1874
Margaret b Alyth 1875
Catherine/Kate b Alyth 1875
Henry b Alyth 1880
Charles b Alyth 1883
John b Coupar Angus 1885
Annie b Coupar Angus 1887
Now, on the 1891 I have William Morrison jnr with Jessie and Kate at the farm that I know was owned by his father describing himself as "Head." There's no sign of the rest of the family, but they must have made the move to Whitefield Farm, Cargill before 1891. Alexander is also on the 1891 census with his family over in Angus. Given that the last two children were born in Coupar Angus I don't believe William and Janet could have been that far away in 1891. Henry and Isabella may have died in infancy, but I can't find a death certificate (if they're on the 1891 census it'll answer that question) and James Morrison definitely spent some time in Edinburgh because he got married there in 1898.
But even with all these clues, there's no sign of the rest of the family! Any suggestions? Could they just have been missed? Are the census records on Ancestry rubbish?