I am a little lost as to how to proceed here - not helped by trying to track down a Smith! To an extent I have a lot of information about Andrew Smith. He was born 22 August 1814 in Prestonpans, son of Andrew Smith, a watchmaker and his wife Marjory Smith. He married Christian Kent on 5 January 1834, and then moved to Tranent, where he is listed in the 1841 and 1851 censuses as a watchmaker. I can't see him in trade lists for Tranent, although his father is clearly listed in them for Prestonpans, but the censuses, and his marriage certificate make it clear he is a watchmaker.
In the 1841 census the family is
Andrew Smith 27
Christian Smith 27
Andrew Smith 7
Jane Smith 4
Thomas Smith 2
Janet Ransay 15
whereas in 1851 Christian had died a few months earlier on the 20th March 1851, leaving father with a large family
Andrew Smith 36
Andrew Smith 16
Jane Alston Smith 13
Thomas Smith 11
Charles Smith 9
Robert Smith 6
Alexander Smith 3
What happens next in 1861 I am not sure. Andrew Smith Jr is married and living in Peebles, I think I have found Thomas in lodgings in Edinburgh, with his brother Charles visiting him, but the rest have disappeared off the map.
Searching through scotlandspeople I see no plausible entries for Andrew Smith's death registration between 1855 and 1920 in East Lothian. In short he seems to disappear - the family has fractured and I am not sure where he ends up.
Any suggestions on how to proceed and where to look would be appreciated.