Gwladys Fenton was Alexander Fenton's first wife and Mhairi was their daughter. I found lots of new information on them.
I am pretty sure that Mhairi Angela McCleod Fenton was born November 1918, possibly November 30. I am waiting for a copy of her birth record from Scotland. Gwladys and 7-month-old, Mhairi Fenton, arrived in Canada from Liverpool, England on July 2, 1919 with several other "Canadian Military Dependents."
Records show that Gwladys died October 23, 1923 (age 36) and was buried in Mount Royal Cemetery in Montreal, Canada. The cemetery confirmed that Gwladys died of chronic pulmonary tuberculosis.
Mhairi Fenton was raised by her aunt Janet McEuen and husband Dr. Charles McEuen. She seems to have spent most of her time growing up in Scotland with several visits to Montreal and England.
You can read more about the Fenton Family here.