The Herries and the McLellans/McClellans were vassals of the Douglases, but not very happy about it.  Following the Black Bull Dinner, when the 6th Earl of Douglas was murdered by the King in Edinburgh Castle in 1440, they saw their chance of shaking off their servidude.  This, of course, did not go down well, and the Douglases sought to bring them to heal, hence the killings.

Whilst there was much infighting between border families, they were united (usually) against the English, and as vassals, the Herries and McLellans would be required to join in the fighting.

When the Black Douglases fell from grace, the Red Douglases (Earl of Angus) saw their chance to take their place. Presumably the Mclellans again saw their chance of shaking off the dreaded Black side of the family.

You proably know that a tutor is someone appointed to run the family business whilst the laird is a minor?

The early Maclellans are not very well documented. This tree shows some thoughts on the subject:

To enlarge, press Ctlr and +

 

This link tells some of the story: http://www.old-kirkcudbright.net/pages/castle.asp

All this was over 500 years ago - I do not think that what happened then matters much now, in terms of relationships.

 

William

The chart is taken from the excellent Stirnet site - membership of which is well worhwhile.

If you want a full history then I suggest Michael Brown's book, The Black Douglases, published by Tuckwell Press.  sadly, it is not in print, but 2nd hand copies should be available.  It deals with the land allocation very well.