FamilySearch has quite a few births/baptisms to Angus McLean and Sarah in Canada, but only three with mother's surname McGillivray or variants
Donald, born 18 December 1854, baptised 8 March 1854 (yes, I know, the baptism is before the birth but that's what the card says), St Georges Parish, PEI
Isabelle, baptised at 3 months old on 18 July 1855, St Georges Parish, PEI
John, born 18 July 1856, St James Parish, Georgetown, PEI, baptised 20 August 1856
There are also records of four children to Angus McLean and Sarah McLean, all in the Presbyterian Church, Wood Islands, Queens, PEI
Hector born 3 April 1864 baptised 22 April 1864
John born 23 December 1865 baptised 22 April 1866
Mary born December 1867 baptised 21 September 1870
Alexander born 24 April 1869 baptised 21 September 1870 (same day as sister Mary)
These are all from digitised images of a typed card index, so presumably there must be some sort of original document from which the information was taken.
I gather that the first typewriters with both upper and lower case were produced in 1878, so this card index must have been created several decades after the baptisms.