I don't have a lot # for James Roy Grant, but in 1851, 1861, 1871 censuses, his son John is always in his h/h. In 1881, James has died and John is head of h/h with only his nuclear family. On the 1879 Historical Atlas map, John J. Grant is Lot 15 2nd Concession. This lot is part of a larger area, Lots 15 -18, which spans the So. Branch of the river, in which other Grants also live: A.J.Grant, Esq., Archibald Grant, Alex Grant, A.J.Grant, A. Donald Grant. In 1861, James Roy had sons named Alex, Donald, and John, so it isn't clear how the Grants in that block of lots relate to each other, but it seems likely that they did relate in some way. (This is assuming that the John J. Grant on lot 15 is "my" John J. Grant).