After Macbeth killed Duncan, both of the brothers went into exile for a while, then Malcolm eventually came back and took the throne as the eldest son of Duncan as most of us would expect. Malcolm nominated one of his sons to be king after he died. However, for some reason Donald became king instead and there was an ongoing war between Malcolm's and Donald's descendants over the throne for multiple generations, but I am having trouble finding out why.
The most useful thing I could find was that the Scottish succession should have passed to Donald as his eldest brother, but not why. Even if Donald should have been king at that point due to the ages of Malcolm's sons, wouldn't that have just made him regent until they came of age?
Could someone please explain why Donald's family believed they were the legitmate heirs over Malcolm's?
I managed to speak to a history student who has shed some light on this, but I am still left wondering why Malcolm decided to ignore the standard rules of succession?
So it turns out that in France, they had a cabal / cadet family who would pass the crown around the brothers of one generation at a time, before passing it onto the eldest sons of the king, and the guy I spoke to said that it was likely that Scotland had the same thing. So on Duncan's death it should have gone to Malcolm, then when Malcolm died it should have gone to Donald. When Donald died, it should have then gone to Malcolm's first son, when the first son died, then onto the second and third sons etc before being passed onto his grandchildren.
So my new question, assuming this is correct is why did Malcolm decide to ignore the rules of succession and go for the traditional "give it to my eldest son"?