Canonicity Problem

So, some external materials, like worksheets and tests, are provided by Cambridge as a supplement to the course. These will sometimes include stories, which often times fill in major plot holes, such as the death of Grumio, and the backstory of Bregans This raises the question as to whether these stories should be considered canon alongside those in the books. Also, it should be worth noting that including these stories may basically provide current students with Cliff Notes for the tests. So, should these external stories be included on this wiki, or considered canon at all?