Andrew McCulloch & wife Catherine Ross had 9 children I know of, all born Calrossie, Logie Easter Parish, Easter Ross:
Andrew b.1819 - d after 1851
Janet b. 1821 - d. after 1861
Ann 1824- 1890
William 1826-1916
Thomas Ross 1828-1890
Alexander 1830-1912
*Margaret b.1833
James Duff 1836-1926
Catherine Ross 1839-1920
In the 1851 Fearn Census Catherine age 50 & Andrew McCulloch, a Mason aged 60 and their children Janet, *Margaret, age 16 Ag.Lab, James and Catherine are at (33) Balnagore.
Balnagore is/was a farm. (this may not be the correct technical term - but thats what it looks like from the road! Might be a steading, an estate?? Only wanted to illustrate that it is not a large settlement population-wise.)
A Margaret McCulloch married a Hugh Munro (or Roy) in Fearn Church Vestry on 2 March 1852 She was residing at Balnagore at the time of marriage [NAS CH3/962/8], so it seems likely it may have been "our" Margaret, though not 100% conclusive.
On the assumption that it might be "our" Margaret I followed her:
Margaret McCulloch and Hugh Munro had (as far as I'm aware) 6 children ; Hugh 1851 (- the result of anti-nuptual fornication CH3/962/8 states) , Anne 1853, Mary 1856, Isabella 1862, Walter 1863 & John 1866 all born Fearn. (odd that there are no Andrews or Catherines, but I did wonder if maybe the child born before the marriage caused a major family fall-out. The McCullochs were a family who had to move Parishes in the disruption of 1843 due to being staunch Free Church supporters - they were "warned out of their land" and had to move from Logie Easter to the "next-door" Parish of Fearn. Maybe the family didn't approve of Mr.Munro. After all, he is mentioned in the Free Church records with an alternative surname of "Roy" and I'm not sure what this implies...?)
Margaret Munro then appears to turn up on several census returns, although her age and place of birth seems to alter substantially:
1871, Loans of Fearn
Hugh Munro H 53 Ag Lab born Fearn
Margaret Munro wife 42 (would expect around 38yrs) born Fearn
Hugh son 19
Margaret [this is Mary?] Dau 14
Isabella Dau 10
Walter, son 8
John, son 5, all born Fearn
1881
Meikle Rhynie, Fearn, Ross & Cromarty, Scotland
Source:FHL Film 0203408 GRO Ref Volume 064 EnumDist 1 P. 9
Hugh MUNRO M 63 M Fearn, Ross and Cromarty, Scotland, Head Occ:Agri Lab
Margaret MUNRO M 55 [expected 48yrs] Fearn
Rel: Wife
Occ: Labourers Wife
Hugh MUNRO U 28 M Fearn, Ross and Cromarty, Scotland
Rel: Son
Occ: Agri Lab
Mary MUNRO U 25 F Fearn, Ross and Cromarty, Scotland
Rel: Daur
Occ: Serv (Domestic)
Isabella MUNRO U 19 F Fearn, Ross and Cromarty, Scotland
Rel: Daur
Occ: General Servant
Walter MUNRO U 17 M Fearn, Ross and Cromarty, Scotland
Rel: Son
Occ: Agr Lab
John MUNRO U 14 M Fearn, Ross and Cromarty, Scotland
1891 Mgt Munro living at Rhynie Farm, a widow, former farm servs. wife aged 68 [expected 58yrs], but born Tarbat. This looks like it is the same family as above as children Hugh 40, Mary 35 and Walter 27 are all still at home - all unmarried farm servants. There is a granddaughter with them too - Mary Ann Fraser aged 9 born Fearn. (so born approx 1881/2 - not got far with investigations into that one yet!)
1901 Living at 20 Smiths House Tain (between Bogbain Farm House and Rosemount House) - Margaret Munro, widow, formerly farm crofter, age 80 [expected 68yrs!] born Tarbat, sons Hugh single 56 unemployed, feeble minded, and Walter single 38, Labourer Agri, living with her.
1905 - Son Hugh Munro died at Rosemount, Tain - Margaret McCulloch stated as mother, so looks like she was still alive.
1922 - Son Walter Munro died 20 Scotsburn Road, Tain. Margaret McCulloch stated as deceased.
1912 Also, in an obituary for Margaret's brother, Alexander McCulloch, who died 1912 at Newmilns, Ayrshire, it states (if you believe all it says in the Newspapers?!) that Alexander had two brothers and two sisters still living - brothers would seem to be James Duff McCulloch (Principal of the Free Church College, Edinburgh died 1926 Glasgow) and William who died in 1916, Kirknewton. Sisters were likely to be Catherine (Mrs Angus Graham, d.1920 Fearn) and Mgt. so Margaret may have died after 1912? This is not conclusive either as I don't yet know what happened to sister Janet, last sighted in the 1861 census.
I have been unable so far to find Margaret's death, despite having what looks like a fairly limited time-frame (1905-1922) to search. She could, in theory, be anywhere in Scotland as I don't know what happened to her other children - they may have moved away from the area. I hoped her death entry might confirm once and for all that she was indeed the daughter of Andrew McCulloch and Catherine Ross... but knowing the way these things seem to turn out, I will not be surprised if she died at such a great age that no one could remember who her parents were.....
I apologise for the great length of this but I felt it was necessary to give as full a picture as I could! Many thanks if you've read this far.

Best wishes
Lesley