Complex sentence: Although John Comyn, Lord of Badenoch, sometimes known as the Black Comyn, was one of the minor competitors, the weight of the family was behind the claim of Balliol, Badenoch's brother-in-law.
Split into simpler sentences: Although John Comyn, Lord of Badenoch, sometimes known as the Black Comyn, was one of the minor competitors. The weight of the family was behind the claim of Balliol, Badenoch's brother-in-law.