I'm sorry Merla, but my ignorance of the various family lines is quite huge so I cannot help.
I have the journals, but they contain none of the trees except that births and marriages are often accompanied by a coding referring to trees that Hugh McColl kept in his files. These are the papers that many of us would give at least one eye-tooth to get a hold of!
You will have investigated the bynames and placenames? Although I am missing any deep knowledge and study, it sounds like Donald came from the fort on the white hill (if there is such a place near Glasdrum at the head of Loch Creran) and John was fairhaired and skinny! Knock means a hill too, and there's a village named Knock on the island of Mull.