Have you seen
- their baptism records?
- their marriage certificate?
- did they die in Scotland, and if so have you seen their death certificates?
- have you found them in all the relevant censuses?
- what were the names and DoBs of the 11 children?
If we can establish exactly what you already have, we can then work on getting more information without duplicating what you have already done.
I see that in the birth indexes the name is sometimes spelled Binnay. In the 1861 census, at Philorth Cottage, Fraserburgh are Alexander Binnay, 35, master gardener, born Belhelvie; wife Isabella, 24, born Rosemarkie; daughter Jane A, 4, born Aberdeen Old Machar; son John A, 2, born Ordiquhill; son William James, 10 months, born Fraserburgh; and sister-in-law Catherine Grant, 16, born Rosemarkie.
I am not seeing them in the 1881 census in Aberdeenshire, other than a 16-year-old George Binnie, born Fraserburgh, a farm servant in Tarves, who might be their son.
Where did you find 'Mildren'? And where did you find a record of Alexander as a tailor?