Hi Sandra
I'm just compiling a timeline with Janet Brown, her siblings, and Ivy, to spot the gaps in info, and guessing where people might be.
And making a wishlist on Scotland People to be sure to only pay for the best search results. You found a possible Ivy as Isabella Caldwell MMN Brown for 1891 (but no clue to the quarter) in Nielston, and I've found on the 1891 census (held in April) an Isabella Caldwell 1 year old in Partick. If the birth is Ivy then it would be March so she'd only be one month old. I need to check how babies' ages were entered. The transcript says 1, so that might be month or year.
Caldwell is a commonish name in the area, as is Brown, but I found a marvellous memorial headstone in Edinburgh that gives lots of family details. The vault or plot of John Brown and wife Janet Skinner, parents of David Miller Brown. An Edinburgh family.
I'm just looking to see if any of Janet Brown's family were alive and in Scotland at about the right time for the 1891 birth and accommodation for them both.
I will update here once I've looked at all the possibilities.