Hi ails81 (Cousin!),
My 4th gg are also Hugh McPherson and Catherine McPhee. I have looked on and off for years to get more info on them, as I also have only seen them on death certificates as well, except for one thing I will describe below.
Children of them include John (my ancestor), Hugh, Jean, Martin, and Duncan. I found one of Duncan's descendants through genealogy tests.
Hugh died a pauper (formally cowherd) in Achateny, in 1879. His son Allan was present. I have his death certificate, and also some census entries for him. He was living with John and John's wife for a while. In addition, I have I have Jean's birth cert from 1812 and some census entries; Martin's birth cert and a census entry; and John's death cert from 1870, along with census entries from 1851, 1861, and 1871. I can send you all of these. I didn't know about Christina.
Are you on GEDmatch? I have my family tree up there, but I can send it to you as well.
The only other thing I have is the text of an old document that was found in a notebook in 2002 when the Clan MacPherson museum was being indexed, entitled "The Macphersons of Ardgour and Ardnamurchan". Some of the info in the beginning is incorrect, but the later info matches up. There was a Donald, whose son was Donald Og ("the younger"), and Donald Og's eldest son was Ewen (Hugh). If this is correct, then your 5th gg is Donald Og, and your 6th is Donald.
"When Catherine Macpherson came down to Lochaber as Lady Cameron of Locheil the usual customs of those days was followed and she brought along as her body guards twelve of her own clansmen under the command of her brother Donald. The twelve Macphersons on coming to Lochaber adopted the name Cameron but Donald MacPherson remained Donald MacPherson and he was the founder of the MacPherson of Ardgour and Ardnamurchan. Locheil went away to France about 1748 but Donald MacPherson remained, and he survived his oldest son. He lived on the farm at Drum na salie which untill then was the home farm on the Locheil Estate. He was spoken of as Donald the eldest or similar while his grandson was spoken of as Donald og or junior from his younger sons there came down to us the Macphersons of Shieldfoot near Acharacle or “the Drovers”. His oldest son Ewen lived at Garvan in Ardgour. He was succeeded there by his oldest son Martain whose family are known as the Macpherson of Ardgour. The second son of Ewen MacPherson Duncan married Annie Henderson from Western Ardnamurchan and followed the occupation of Cattle heard and sheepeard."
The info on Ewen, Duncan and Annie match up with both my family tree and the family tree of the person I found through genealogy tests.