Update to possibility that my Alex Grant's wife was Anne Cameron: I've been going back through my massive accumulation of paper and found the marriage bond for Alex's son, James Grant and Catherine Dingwall. It is signed by James Dingwall and John Cameron.
I don't know whether this means Alex Grant had died by this 1828 marriage, but it looks like James' bond was put up by a Cameron relative. Would a non-relative have paid it?
I've also learned that the Crown patent for Lot 15W 2nd Con. SSRR went to Alex Grant in 1802 and was transferred to James Grant in 1828 three days before his wedding. (I don't have a record yet of the means of the deed transfer).