A new line to work on....
I have been looking at the names of Ann McMillan's children with Allan Stewart. Given his parents names look to have been John and Ann, the next stand out names are Dugald and Mary. So, wondered if Allan and Ann used Scottish naming pattern (lots of links on this such as
www.halmyre.abel.co.uk/Family/naming.htm - not always followed, or to the order, but amazing always how this did influence the naming of children).
Working on the names Dugald McMillan and Mary brought up this potential marriage, which is very close to the areas we have for the family in Argyll:
www.familysearch.org/ark:/61903/1:1:XTK4-68F - Dougald MacMillan and Mary MacPherson marriage or banns in 1819 in Acharacle.
The first hard facts you have for the family is from 1841 and the children all showing to be living with an Archibald and Mary McLaughlin. Everyone showing as born outside of the county:
Archibald Mclauglin 30 cotton dyer
Mary Mclauglin 35
Ann McMillan 15
Hugh McMillan 15
John McMillan 10
Janet McMillan 9
Catharine McMillan 8
Angus McMillan 5
Angus Mcgilvery 15
Address: Renton Back St, Cardross Dunbartonshire
Ages as you know were rounded down to the nearest 5 years this census. Children under 15 were supposed to show at their actual age.
You wondered who this couple was earlier on. Could she be their mother? If Dugald McMillan died and mother Mary McPherson (theory!) remarried. There is a corresponding marriage to fit this possibility:
www.familysearch.org/ark:/61903/1:1:XTRN-ZJG - Archibald Mclachlan and Mary McPherson marriage or banns in Cardross in 1838.
This would explain this household in 1841. Need further corroboration though...
Monica