Apologies for the late reply, been a busy day!
Monica - when Elizabeth was married in 1907, her address was the same as her husband in Fountainbridge. Her husband's family lived in Fountainbridge in the 1901 Census but at a different number. I'm guessing they were staying with his family, who had probably moved up the road.
When Annie was married in August 1915, her address was in the Potterrow.
I have found Elizabeth in the 1911 Census living just with her husband and two young daughters - Isabella age 3 and Jeannie age 1 in Grove Street. Checking the addresses on the birth certificates of her other children, I'm sure that Elizabeth was living at the Potterrow address from 1915 until at least 1931. I checked the Valuation Rolls, hoping to find James or Isabella as the registered occupant thinking it may be a family address, but Elizabeth is the named occupier tenant from 1920 to 1930. Elizabeth was probably the tenant occupier in 1915, when Annie was married, but the VR is made up before the date of Annie's marriage.
As Annie married during WW1 her husband was on active service with the Argyll & Sutherland Highlanders, his address on enlistment was his parents in Paisley. Annie's first child was born in 1917 in Edinburgh, while Annie's husband was still on active service. It could well be that Annie was staying with family, possibly at the Potterrow address. I haven't got the birth certificate to check the address but I'll get it when I go to SP. After the war they lived most of their married lives in Elderslie, just outside Paisley.
In answer to the last question about when Isabella moved, I know that initially she went to live in Elderslie with Annie but I don't know when or for how long. When she became ill Elizabeth went to Elderslie to pick her up and took her to her new address in Niddrie, where she died in 1945.
Sadly, still no clue where James was living but I'll do some more work with the Valuation Rolls, which give occupations. That will need to be a visit to SP - which will be another busy day!
Kay - the marriage definitely looks right but I don't know how we can prove it's our Jeanie/Janey. When I saw she had a younger sister called Isabella, I wondered if she had taken on her children but that still doesn't explain where the name Cumming came from. I'm losing the plot slightly - I'm very grateful for your fiddling!
