Hi Peter,
At this stage, we are not saying that Casey stayed with Buchanan's, but just trying to get things to work out to suit what little we know already. Margaret may have been an illegitimate Casey but then her mother married a Buchanan, and she may have used her step dad's surname or registrar used that surname for her name.
This is only a theorem and we do not have proof yet. I have been at the search for 4 days now, and I do not think I am any further forward. I have had theories but no proof. The passenger list does not give enough actual information, only gives "Linlithgow" as the county of Linlithgowshire. The family looks OK, but we cannot get any census information to back it up.
The lack of marriage certificate for William Henderson and Margaret Casey is annoying, I have looked at Catholic records as well as Church of Scotland, and nothing turned up. The death certificate gives ages of children but no names, and we do not know who the 9 children are.
So no real progress made yet. Something may turn up, got to keep positive.
Tom Buchanan