I recently completed a PhD and I'm now applying for post docs, so I need to provide references with these applications. To me it seems natural to provide both my PhD supervisor and master's thesis supervisor as a reference, in addition to one external professor who knows my work. I will of course ask them for permission in advance.
However, in my case the PhD and MSc advisors have a close family relationship. I worked with each of them separately as well as jointly with the three of us. Is it appropriate to include both of them as referees to one application or list them both as references on my CV?