This is a very useful article from Sam Prochazka on the steps that can be taken to avoid unnecessary conflict when working with family. 

I particularly agree with the point on making criticism constructive. We hear too often about general discussions descending into a slanging match where the injustices (perceived or otherwise) that a sibling experienced in childhood are bought up. 

Appreciating our tone and language when communicating is also important and as we are dealing with family members it is easy to forget this.