I see in previous posts John's parents were William Grant and Sarah Green.
No, what you saw in this thread was my statement that John, son of William Grant and Sarah Green was born in 1826. Don't take that as definite evidence that it is the same John Grant. There were 837 Grants in the parish of Cromdale Inverallan and Advie in 1841, so there is plenty of scope for getting the wrong one.
FWIW the Grant household at Knockanbuie in 1841 consists of John, 48; Catherine, 44; John, 15; Mary, 11; May, 9; Margaret, 7; and Ann, 5 (from FreeCEN).
At Knockanbuie in 1851 are John Grant, 65; wife Catharine Grant, 57; daughter Marjory Grant, 20; and a lodger.
These both look like the family of John Grant and Katharine McDonald: John, 1825; Mary, 1828; Marjory, 1830; Margaret, 1833; Ann, 1836. (May is often used as short for Marjory.)
Mignon (in the older post on RootsWeb) says there were two couples named William Grant and Sarah Green in Cromdale about the same time. I am sure she has a good reason for saying so, but she must have found something that I have not found in my rather superficial searchings online.
The family of William Grant and Sarah Green (from the 'community indexed' IGI) are Elizabeth, 1812; Charles Lenox, 1814; William, 1816; Sarah, 1818; James, 1820; Francis, 1822; Ann, 1824; John, 1826; Isabella, 1827. FreeCEN lists at High Street, Grantown a household consisting of William, 60, innkeeper; Sarah, 50, born England; William, 25; Sarah, 20; Isabella, 13; Thomas, 9 and 5 servants. I think that this looks like the family of William Grant and Sarah Green.
There is a household of William Grant, 50, dyer with wife Sarah, 55 in Main Street, Grantown with children who match the family of William Grant and Sarah Miller.
There is a third household with William Grant, 60; Sarah, 50; Jane, 40; Ann, 30; and William, 15 at Culinduim. The 1851 clarifies that Jane, 48 and Ann, 40 are the daughters of William Grant, 76; but if the ages are correct Jane cannot be the daughter of Sarah, who is 60, so Sarah has to be a second wife.
I've rambled a bit, but the point is that those are two John Grants of the right age to be the head of the household at Knockanbuie in 1861/1871/1881. One of them was the son of John Grant and Catherine McDonald, who were at Knockanbuie in 1841 and 1851 and the other was the son of William Grant and Sarah Green, who did not live at Knockanbuie.
John Grant in Knockanbuie gives his age in 1861 as 36, in 1871 as 45 and in 1881 as 55. So if he is being accurate he was born between 1824 and 1826.
There are six more John Grants in the parish register of Cromdale Inveralland and Advie baptised between 1824 and 1826. So you must not believe anyone who tells you who 'your' John was when there is a primary source for the information.
You really
need those death certificates!