She left Isaac, heading back to Detroit, Michigan, around 1924, to live with one of her daughters (likely Nanny). According to an interview with Violetta (her niece, and adopted daughter) in 1988, she was Louisa’s sister. Violetta also said that she was married before to someone else before Isaac, which is where her surname Thompson is from (verified by Manitoba Vital Statistics Marriage record). She supposedly had 2 sons and 2 daughters from that marriage, and the husband and two sons all died within 6 months of each other in the British Isles (some notes say Ireland, others say England... believe it is Ireland), from Black Measles. She came across to North America after this with her two daughters.
The 1916 Saskatchewan census shows her being born around 1874, and having immigrated from England in 1882, which contradicts a fair bit of this story (if the census info is accurate). It also spells her name as “Carey”.
The 1921 census shows her still in Invermay, with her first name listed as Caroline, and her immigrating from England in 1880. She is shown being older than Isaac, being born around 1872/1873.
There is a record of a Caroline R Holley (although it shows her as widowed) living in Port Huron, St. Clair, Michigan (just northeast of Detroit, and right next to Sarnia, Ontario), in the 1930 USA census. She is shows as 57, born in England around 1873, and having immigrated in 1908. She is shown as a servant in the William C Button household). Not sure if this is the same person. Comparing with the new data from the 1921 census, this could very likely be her.
It should be noted that if a spouse had not heard from a separated spouse for 7 years, they could legally re-marry without a formal divorce around this time. This is believed to have happened before Isaac married a 3rd time to Mabel Palmer.