This is my first post, so here goes

I am stuck trying to find information on Alexander Moncrieff - he married Jane Skene 8 Jun 1821 in Old Machar, Aberdeen.
I could post this on the Aberdeen site, but, though their children Thomas, 1822, Alexander 1824, James 1826, Jane 1827, Andrew 1821 and David 1833 where all born in Aberdeen (Old Machar and St Nicholas), all are living in Perth across every census from 1841 onward, also, Jane Skenes' birth was St Nicholas but her death was recorded in Perth too, she is also on several census records as living in Perth. So I make the assumption that he moved to Aberdeen from Perth, got married had kids then moved back to Perth.
But I can find no trace of Alexander since the birth of David in 1833, I can't find a death certifcate that would connect him to Jane Skene and list his parents so i can verify. I was thinking about going with a process of elimination and using the naming pattern as guidance as I'm fairly sure his father's name was Thomas, but there are so many Thomas, Son Alexander combinations I'm not sure where to go. Any advice would be greatly appreciated.