Re: Ewan Mackay/McKay-Boggierow death
He would have been buried in the parish kirkyard at Fordyce. See https://www.geograph.org.uk/gridref/NJ5563 and discussion at https://www.rootschat.com/forum/index.php?topic=504689.0
The cloth was called a Mortcloth. There are often records of payments for the hire of a mortcloth in the Kirk Session records, but these documents cannot (yet) be viewed on Scotland's People.
In the 1841 census Ewan's age is given as 50. In 1841 adults' ages were supposed to be rounded down to the nearest 5 years, which means that he could have been any age from 40 to 54. The census was taken on 7 June 1841, so if his age was accurate he was born some time between 8 June 1786 and 7 June 1791.
If he was poor enough not to have a headstone it is not likely that his death was reported in the newspapers. The most likely newspapers, if he was mentioned at all, would have been the Banffshire Journal and the Aberdeen Journal and Aberdeen Weekly Journal. Both of these are in the British Newspaper Archive https://www.britishnewspaperarchive.co.uk. You can search it for free but if you want to see a full entry you need a subscription to the collection or you can view it with a subscription to FindMyPast. It is not easy to search because it can't accommodate spelling variations. I have had a look and did not find anything.
Boggierow is a single farm/croft - see https://maps.nls.uk/geo/explore/#zoom=15&lat=57.68158&lon=-2.70540&layers=5&b=1. If you want to know the number of people living there in 1842, you could get an idea by going to the 1841 census at https://freecen1.freecen.org.uk/cgi/search.pl and 'walking' the enumeration district looking for mentions of Bog(g)ierow. Start by searching for Alexander Bannerman, aged 40, in the parish of Fordyce and use the 'previous household' and 'next household' buttons to find all the households at Bog(g)ierow. I would be surprised if there were more than three or four households there.
I see that the recorded children were John 1820, Janet 1821, Anne 1824, William 1826, Alexander 1828, Ewan 1830, Margaret 1832, Peter 1837, Joseph 1837 and Jane 1841. It looks as if Margaret Russell or McKay, mother's maiden surname Lawrence, died in Fordyce in 1864 aged 65. She could be the daughter of John Russell and Janet Lawrence, baptised 28 January 1798 in Rathven. You can verify this by viewing her death certificate on Scotland's People if you don't already have it. Have you seen all the children's baptism records? Are the witnesses named and if so do they provide any clues?
If this is her, then Ewan and Margaret do not seem to have followed the naming tradition exactly, unless Ewan's father's name was also John, and if that were the case you would expect the second son to be Ewan. Therefore, while it is possible that his parents' names were William and Anne, you can't be certain. Also, you know that, according to the 1841 census, he was ***not*** born in Banffshire, which leaves 32 other counties where he could have been born. It has been suggested that his parents were William McKay and Ann Gray, but all their recorded children **were** born in Banffshire.
As for trees on Ancestry or any other commercial web site, the golden rule is: never believe anything you find online, unless it is an image of an original document, and even then be wary as mistakes are not unknown. Just because there are four trees suggesting this does not lend any more weight to that idea than one tree, or forty-one trees, because people copy others' trees without checking them, so if the first one is wrong, then all the copied ones will be wrong as well.
If I were you I would take a very close look at those online trees, try to work out which was the first one submitted, and then contact whoever submitted that tree and ask them if they have any solid evidence to verify that William McKay and Ann Gray were the parents of Ewan McKay.
I'd sum up by saying that **if** the 1841 census is wrong about where Ewan was born, he **might** be John, son of William McKay and Ann Gray. But in my opinion the chances are that he was from further north and west, and unless you can find some other primary source, which is not likely, you will never be able to say with certainty who his parents were. Sorry to have to say that, but facts are chiels that winna ding.