The 1861 census household for Thomas and Robert Smith ...
Margaret Edgar 64 Widow Scotch
Janet Edgar Daur 30 Scotch
Margaret Edgar Daur (

) 14 Native (would mean b. in New Brunswick)
Robert Smith 12 Grandson West Indian
Thomas Smith 10 Grandson West Indian
On Ruben's marriage to Theotiste his mother' name is given as Ann EDGAR.
Can't see Margaret (above) being the daughter of the elder Margaret, given her age? Perhaps actually a granddaughter? Age could also be wrong, of course.
PB