I am pleased to report a success.
Yesterday I was asked to look for a marriage in Scotland for a couple who emigrated to Canada arriving in May 1881 They were Mr & Mrs Douglas accompanied by a nephew.
I was told their names were David or John Douglas and Jane Rose Brodie.
Since they had no children, I reckoned they married quite soon before 1881, but no combination of the names was yielding any results.
The Canadian descendant had identified the Brodies in Dalry Ayrshire and the Douglases in Leith. Being in Ayrshire, I started with the Brodies. Jane is in 1871 census but not 1881 which fitted, but any Jane Brodie marriages were to other men.
Then I just tried for David Douglas marriages to Jane blank and 3 came up. I tried the one closest to 1881 and bingo!
David Douglas married Jane Rosie, daughter of John Rosie and Margaret Rose. Rosie not Brodie! The Rose middle name stems from her mother's maiden name.
The Douglases did match the family identified. I found David and Jane in Edinburgh in 1881 and saw she was born in Orkney. So far I haven't managed to find the family any earlier although there are lots of Rosies in Orkney and Caithness. None of them quite match. Names of John, Margaret and Jane are not distinctive enough!