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Wouldn't it be easier to use multiple source files and then including the question subfiles and answer subfiles at the appropriate points? It sounds like a job for make rather than pure LaTeX

Have you looked at the natbib package? From your post I assume you are using the harvard package with bibtex. Natbib offers the features you seem to be asking for. The harvard style file despite it's name cannot do what you are asking it to do. \usepackage natbib and citation styles would seem to ...