The James Rae who was married to an Agnes Landells in 1882, does not seem to have had a middle name Low. He died in 1920 and Agnes died in 1926 see
https://billiongraves.com/grave/James-Rae/25037286. He and Agnes possibly had a daughter, Agnes Hogg Rae born in 1888 at Camlachie, a son Joseph Landells Rae in 1886, a David Landells Rae in 1890 and possibly a Jemima Rae in 1893, all Camlachie, as well as a James in c1885 and an Andrew in c1896. All living at Camlachie in 1901 at 9 Gate Side Street.
So, a James Rae and an Agnes Landells having two daughters with the same names, Agnes and Jemima, as those mentioned in opening post. Coincidence or...?
Ticketty Boo...as has been said by others, your great grandmother Jemima's birth certificate (and telling us the year), would be a good place to start and give some solid info on who her parents were. Your first post gives no indication of any dates, so we are looking to 'fit' people into the limited info you have provided, who may or may not be red herrings.
Where did you glean the info that her mum was an Agnes Landells? Where did you glean the info that her dad was a James Low Rae rather than just a, for example, James Rae? Why do you suspect James' mum was a Jessie? The more we know where your details come from, the easier it might be to untangle any rogue ones and avoid mixing up quite distinct family groups, who both happen to feature the names James and Jemima, and with a Jessie in one too.