I have read somewhere in the past that there were a branch of Grants referred (not sure if that is the correct word)to as the Glenmoriston Grants of Strasthspey/Ogilvie branch??
Perhaps this might be a question to direct to Anne Neuman UE
who posts a lot of important Grant information on this forum and who might give us some clues here. Maybe their ancestors were of Strasthpey branch?