Post Doc referees related to one another 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?
I don't see any problem with listing them separately, just as if they were any two other people.  Of course it is good to have an additional reference who is not related (and from a different institution).

I think it would be inappropriate to omit one of them, or lump them together with the other, solely because of their family relationship.  It would look like you are devaluing their professional opinion for reasons unrelated to their professional work.