I have a paper to which I am 3rd author from my previous postdoc, and recently I got another postdoc in another institution. Is it fair and ok to add the new affiliation now, at the proof stage?
Is it fair and ok to add the new affiliation now, at the proof stage?
Yes. You could insert a footnote saying that the research feeding into the paper was carried out and completed while you were affiliated with university -1 in their lab 'so and so'.
This way, everybody is happy, and you're transparent about your whereabouts.