Citing a paper that led to the discovery of another Whilst reading a paper I discovered another and I am now building upon the latter. Should I cite the former paper, since that's how I discovered the latter? Or does it suffice to cite only the latter?
Unless I misunderstand, the question comes down to "Publication A has cited Publication B, which is a primary source. Can I also cite Publication B, or would that be plagiarism?".

The answer is "Yes, it's fine for multiple people to cite the same primary source".