Perhaps the way forward would be to start with what you know about Harriet Mary Macgillivray
Rather than taking a wild guess that she may have married another Macgillivray.
You probably already have this info but for anyone researching, could you confirm if it is the correct family
More information should have been given in your original post, which would have avoided people wasting more time than necessary following the family.
Is this your Harriet Mary Macgillivray (with a McTavish connection)
Born 14 March 1881 - North Knapdale, Argyll, Scotland.
Parents - Angus Malcolm Macgillivray - Mother Mary Mctavish
Bellanoch P. School 1 North Knapdale, Argyll
1881Angus M McGillivray 29 Teacher Of Lab. School
Mary McGillivray 30
Harriet Mary McGillivray 3 Weeks
Christina McLean 50
Mary Johnstone 15
School House Bellanoch North Knapdale Argyll 1891 (No mother Mary on this census - could she have died
)
A U MacGillivray 28 Head Master of P S
Harriet M McGillivray 10 Daughter
Flora McGillivray 70 Mother
Mary A MacInnes 20 Servant
Father seems to have passed away 25 May 1894 as per probate entry for Angus Malcolm Macgillivray - of Bellanoch Lochgilpinhead school master died 25 May 1894 - confirmation of Catherine Campbell or Macgillivray - sealed London 15 September
Glenstive School House Ardchattan and Muckairn 1901
Harriet M MacGillerray 20 Teacher in public school.
Catherine Maclean 29 cousin - nurse domestic.
Can't transcribe 1911 but someone of that name is living in London - could that be your Harriet
Previous thread which mentions the McTavish family and William being the Govenor of the Hudson Bay Co (HBC)
http://www.rootschat.com/forum/index.php?topic=674044.0http://www.biographi.ca/en/bio/mactavish_william_9E.htmlhttps://en.wikipedia.org/wiki/William_Mactavishhttp://timemachine.siamandas.com/PAGES/early_manitoba/William_Mactavish.htmSandra