After having thought for ages that the Al(l)ison ( Also known as "Alice") Downie, who was born to James Downie and Elizabeth Bowie 10th May 1859 in Linlithgow had married an Andrew Lockhart and lived in Edinburgh, I've checked her out - and now don't think she's the right one.
Do you mean that you are looking for the daughter of James Downie and Elizabeth Bowie, and you now realise she isn't the one who married Andrew Lockhart, or that you are looking for the wife of Andrew Lockhart and you have realised that she isn't the one whose parents were James Downie and Elizabeth Bowie? Those are two rather different quests, and it would be useful to know which one is yours.
There are seven marriges of Ali* Downie between 1875 and 1911 in the Scotland's People index. None of them married an Andrew Lockhart. Nor is there a marriage of an Andrew Lockhart to a Downie with any other given name.
There is a marriage of Andrew Lockhart to Alison
Rennie in 1878. This couple may be the one at 3 Dunbar Street, Edinburgh in the 1881 census, with son David, aged 5 months. I note that this Alison is said to have been born in Midlothian, and that she is 27. If that is accurate, it gives a birth year of 1853/1854.
There are four deaths of Ali* Downie, born 1859 plus or minus two years.
Alison Downie or McDonald, aged 37, 1898, Dirleton (birth 1860/1861). This could be the one who married James Haldane McDonald in Whittinghame in 1883.
Alison Downie or Wilson, aged 62, 1921, Gorgie (birth 1858/1859). This could be the one who married Peter Wilson in Edinburgh St Andrew in 1887. If you are trying to find out what became of the daughter of James Downie and Elizabeth Bowie, I reckon she is the least unlikely.
Alice Anderson Downie or Peattie, aged 68, 1929, Colinton (birth 1860/1861). Can't find this marriage.
Janet Alice Downie, aged 91, 1952, Leith (birth 1860/1861). Almost certain to be the daughter of Alexander Downie and Joan Brotherton Roberts, born 21 November 1859, and never married.
I can't seem to find a likely spouse, nor can I (understandably if she married) seem to find a death record
It might be understandable in England, but in Scotland the death of a married women is indexed under both her maiden surname and her husband's surname, and the death certificate should tell you the full names of both her parents, including her mother's maiden surname.