I am sorry for the delay in getting to you but I have been out of province since June 16th.
Info on your specific McLeods/McMillans I have not seen but I do know there was a Mary McMillan married to a Captain Alexander McMillan whom moved to the Fitzroy area sometime after the War of 1812. Mary McMillan was a daughter of a John Roy McMillan of 24.5 Lochiel Twp, Glengarry. Are your McMillans descended from these two .... I do not know.
As for the McLeods when I get home mid-September, I will look again at my McLeod info.
I will keep looking.